Category: Research Guides

GHK-Cu is a copper(II) complex built on glycyl-L-histidyl-L-lysine, a three-amino-acid peptide that holds a single copper ion tightly enough to turn the powder blue. That colour is a quick visual clue, and it’s also the first thing to check when a vial arrives.

So what is GHK-Cu at the level of atoms and numbers? It’s one of the smallest and best-characterised copper peptides in the research catalogue, with a crystal structure, a PubChem record and a CAS number of its own. It’s also listed with at least three different formulas, which confuses plenty of buyers.

This guide covers the molecule, how copper binds to it, why those formulas differ, and how to confirm identity on a COA, using our GHK-Cu 50 mg as the example.

What Is GHK-Cu?

Quick answer: GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (Gly-His-Lys). The peptide binds one Cu²⁺ ion through nitrogen atoms in its glycine and histidine residues, forming a blue coordination complex. It was first isolated from human serum in 1973 and is now made synthetically for laboratory research.

The same molecule carries several names, depending on who’s writing the label:

• GHK-Cu: the common research name, from the one-letter codes G, H and K plus copper.
• Copper tripeptide-1: its INCI name, used on cosmetic ingredient lists.
• Prezatide copper: its nonproprietary name, listed in PubChem under CAS 89030-95-5.
• Copper peptide or GHK copper: looser labels used by suppliers.

The origin story is a dated one. Loren Pickart and M. M. Thaler reported the tripeptide from human serum in Nature New Biology in May 1973, and a synthetic version followed in a paper that September. All research material today is synthetic.

GHK vs GHK-Cu: What’s the Difference?

Quick answer: GHK is the free tripeptide Gly-His-Lys with no metal bound. GHK-Cu is the same peptide carrying one copper(II) ion. They have different formulas, molecular weights, and CAS numbers, so a COA must state which form the vial contains. “Copper peptide” usually means GHK-Cu, though it can describe other copper complexes too.

Property	GHK	GHK-Cu (prezatide copper)
Formula	C14H24N6O4	C14H23CuN6O4⁺ (PubChem record for the CAS below)
Molecular weight	340.38 g/mol	402.92 g/mol
CAS	49557-75-7	89030-95-5
Appearance	White to off-white powder	Blue to blue-violet powder
Charge	Neutral record	Listed as a +1 cation
PubChem CID	73587	71587328

When a supplier calls its product a GHK-Cu peptide, the copper form is what the label promises, and the CAS number should be 89030-95-5. The quickest field test is colour. A free GHK sample looks like any other white peptide powder, while the copper complex is unmistakably blue.

GHK-Cu Structure: How Copper Binds the Peptide

Quick answer: In GHK-Cu, the Cu²⁺ ion is held by three nitrogen atoms from the peptide: the glycine amino nitrogen, the deprotonated amide nitrogen between glycine and histidine, and the histidine imidazole nitrogen. A fourth site is filled by another ligand, which in the crystal is a carboxylate oxygen from a neighbouring GHK. This coordination gives the complex its blue colour.

Amino Acid Sequence and Stereochemistry

The sequence runs glycine, histidine, lysine, from the free amino end to the free carboxyl end. Glycine has no side chain and no stereocentre. Histidine and lysine are both the L-form, which gives the molecule two (S) stereocentres, as its IUPAC name records. The lysine side chain ends in a free amino group that stays away from the copper and carries a positive charge.

Copper Coordination Sites

The Cu(II) ion rests in a pocket formed by the first two residues. Three nitrogens grip it:

1. The glycine α-amino nitrogen at the N-terminus.
2. The amide nitrogen of the Gly-His peptide bond, which loses its proton to bind the metal.
3. A nitrogen on histidine’s imidazole ring.

Those three donors and the copper form two small chelate rings, which is why the complex holds together so well. In the X-ray structure reported by Hureau and colleagues in 2011, the fourth position is taken by a carboxylate oxygen from the lysine of a neighbouring complex, giving a square-pyramidal arrangement. In solution, water or other ligands can occupy that position instead.

GHK-Cu structure, with the three peptide nitrogens that bind copper(II) highlighted.

Why the Powder Is Blue

Copper(II) has nine electrons in its outer d orbitals. When nitrogen atoms bind the ion, those orbitals divide into slightly different energy levels. The electrons can jump between them by absorbing visible light from the orange-red end of the spectrum, and the light left over reaches the eye as blue. A powder that looks white or pale grey has little bound copper.

GHK-Cu Molecular Weight and Formula: 1:1 vs 2:1

Quick answer: Most suppliers list GHK-Cu as the 1:1 complex, C14H22CuN6O4, with a molecular weight of about 401.9 g/mol. PubChem also lists a 2:1 form (two peptides per copper, C28H46CuN12O8), which has a much higher weight. Check which form a COA reports, because the expected mass-spec value depends on it.

The confusion comes from hydrogen counting. Binding copper strips protons from the peptide, and each database record counts them differently.

Form	Formula	MW (g/mol)	Source
Free GHK	C14H24N6O4	340.38	PubChem CID 73587
GHK-Cu 1:1, neutral	C14H22CuN6O4	401.91	PubChem CID 165429100
GHK-Cu 1:1, cation (CAS 89030-95-5)	C14H23CuN6O4⁺	402.92	PubChem CID 71587328
GHK-Cu 2:1 (bisprezatide copper)	C28H46CuN12O8	742.3	PubChem CID 9831891

A fourth figure turns up on some product pages: C14H24CuN6O4 at about 404. That figure is GHK plus one copper atom with no protons removed, a convenient sum that has no database record of its own. The three 1:1 figures, 401.9, 402.9, and about 404, all describe the same complex, so the useful question for any COA is which one the lab used as its reference.

Physical and Chemical Properties

Property	Detail
Appearance	Blue to blue-violet lyophilized powder
Solubility	Soluble in water or DMSO for assay preparation
Storage (powder)	-20 °C, dark and dry, in the sealed vial
Moisture	Hygroscopic, so let the vial reach room temperature before opening
pH sensitivity	Copper binding depends on pH; strongly acidic conditions protonate the binding nitrogens and release copper

The pH point is the one that catches people out. Copper binding needs the amide nitrogen to lose its proton, so at low pH the complex comes apart and the blue fades.

How to Read a GHK-Cu COA

Quick answer: A GHK-Cu COA should confirm three things. HPLC purity of the peptide, with a chromatogram. Mass-spec identity matching the expected mass for the stated form (1:1 or 2:1). Copper content, by ICP-OES or titration, showing the copper is actually bound. Also check that the lot number, test date, and testing lab match your vial.

A Life Link Research GHK-Cu COA (MZ Biolabs, lot 2024-06-26) with the HPLC and mass-spec results labelled.

HPLC Purity

Look for a chromatogram with one dominant peak and a peak table showing area %, plus the method and detection wavelength. On the earlier MZ Biolabs report pictured above, the GHK-Cu peak elutes at 6.02 minutes and accounts for 99.93% of the area, with one small peak at 5.62 minutes making up the rest. A tiny tripeptide elutes early on reverse-phase columns, so a short retention time is normal here.

Mass Spec: What Mass to Expect for GHK-Cu

Electrospray mass spec often shows two signals for GHK-Cu. Some copper falls off in the instrument, so free GHK appears near m/z 341, its protonated mass. The intact complex appears near m/z 402. On the same report, the lab expected a monoisotopic mass of 402.10 Da and measured 402.13 Da. Seeing both peaks is ordinary; seeing only 341 means the copper complex wasn’t confirmed. Our guide to HPLC vs mass spectrometry explains why the two tests answer different questions.

Copper Content and Colour

Copper content is measured separately, usually by ICP-OES, an elemental analysis method, or by titration. In a 1:1 complex, copper makes up roughly 16% of the mass. A colourless or pale powder suggests free GHK, whatever the label says, so colour and copper content should agree.

Lot, Date and Lab Checks

Finish with the paperwork. The lot number on the COA should match the vial label, the test date should fit the batch, and the lab should be named with a way to check the report. Reports issued with a verification key can be confirmed on the lab’s own site. Our guide on how to verify a peptide COA covers all six checks.

What Is GHK-Cu Studied for in the Lab?

Quick answer: In laboratory research, GHK-Cu is used as a copper-binding and copper-transport model, and in cell-based assays that measure oxidative-stress markers and extracellular-matrix gene expression. Published work is mostly in vitro and animal studies. Each result applies to its own model and does not show an effect in humans.

Here’s how the main lines of work divide by study type:

Assay type	Study type	Reference
Copper coordination and redox chemistry of the complex	In vitro (chemistry, X-ray)	Hureau et al., 2011
Oxidative-stress markers and peroxiredoxin 6 binding in RAW264.7 macrophage cells	In vitro and animal (mouse)	Bian et al., 2024
Extracellular-matrix readouts	Animal (rat)	PMID 25731775
Mitochondrial-function and stress-pathway (DAF-16/SKN-1) assays	Animal (nematode, C. elegans)	Wen et al., 2026
Gene-expression profiling across cell lines	Review of Connectivity Map data	Pickart and Margolina, 2018
Oxidative-stress literature	Review	Pickart et al., 2012

The 2026 nematode study is the newest entry, published in Biogerontology in May. Read each row as a description of the model and the measurement. A result in one cell line or one species belongs to that model, and the table makes no claim beyond it.

GHK-Cu in Multi-Peptide Blends

GHK-Cu is often the largest component by mass in multi-peptide blends. In the BPC-157 + TB-500 + GHK-Cu combination, for example, it’s 50 mg beside 10 mg of each of the others. That makes its COA entry easy to overlook. Each component needs its own identity result, and GHK-Cu needs the copper-complex mass near m/z 402, ideally alongside a measured amount. Our BPC-157 + TB-500 + GHK-Cu blend guide walks through a three-component example. The four-compound BPC-157 + TB-500 + GHK-Cu + KPV kit adds KPV to the same trio, so its documents need four identity results.

Is GHK-Cu Legal? Regulatory Status in 2026

Quick answer: GHK-Cu is sold in the US as a research chemical and is used as a cosmetic ingredient under the INCI name copper tripeptide-1. It is not an FDA-approved drug. Research-grade GHK-Cu is sold for laboratory use only.

The dated record:

• Drug status: NPR reported on 7 September 2026 that GHK-Cu “isn’t an approved drug,” and topical copper-peptide products have been sold for decades.
• Compounding: the FDA’s bulk drug substances page, current as of 22 April 2026, lists a GHK-Cu nomination among those withdrawn.
• Research supply: research-grade material is sold for in-vitro laboratory work under research-use terms.

Buy GHK-Cu 50 mg with a Batch COA

Our GHK-Cu comes as 50 mg of blue lyophilized powder per vial. Identity and purity are tested on every batch through Janoshik Analytical and US-based laboratories, with current and earlier reports kept on the product’s certificate page. To find the batch COA, open the product, click View report and match the batch number to the vial label. Orders placed before 2 PM PST ship the same day from California by UPS 2-Day Air.

FAQs

What does GHK stand for?

GHK stands for the three amino acids in the peptide, written in one-letter code: G for glycine, H for histidine, and K for lysine. The full name is glycyl-L-histidyl-L-lysine. Adding “-Cu” marks the form with a copper(II) ion bound to the glycine and histidine end.

Is GHK-Cu the same as copper peptide?

Usually, yes. “Copper peptide” on a label almost always means GHK-Cu, also listed as copper tripeptide-1 or prezatide copper. The phrase can technically describe other copper-binding peptides, though, so the sequence Gly-His-Lys and CAS 89030-95-5 on the COA are the reliable identifiers.

What is the molecular weight of GHK-Cu?

The 1:1 complex weighs 401.91 g/mol as a neutral formula (C14H22CuN6O4) or 402.92 g/mol as the cation; PubChem links to CAS 89030-95-5. The 2:1 complex, two peptides per copper, weighs about 742.3 g/mol. Free GHK without copper weighs 340.38 g/mol.

Why is GHK-Cu blue?

The colour comes from the copper(II) ion. Bound by three nitrogen atoms, copper absorbs light from the orange-red part of the visible spectrum through d-d electron transitions, so the light that remains looks blue. Free GHK without copper is a white powder.

What should a GHK-Cu COA include?

A complete GHK-Cu COA shows HPLC purity with a chromatogram and a mass-spec result near m/z 402 for the copper complex. Ideally, it also reports how much copper is present, measured by elemental analysis. Add the usual paperwork: a lot number matching the vial, a test date, and a named, checkable lab.

How should lyophilized GHK-Cu be stored?

Store the sealed vial of powder at -20 °C, dry and protected from light. Because the powder pulls in moisture, warm the closed vial to room temperature first and open it only then. A steady blue colour is a simple visual check that the copper complex is intact.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

All products are supplied for in-vitro laboratory research by qualified professionals. Read the full research use disclaimer.

References

• PubChem CID 71587328, prezatide copper (GHK-Cu): https://pubchem.ncbi.nlm.nih.gov/compound/71587328
• Pickart and Thaler, Nature New Biology, 1973 (PMID 4349963): https://pubmed.ncbi.nlm.nih.gov/4349963/
• PubChem CID 73587, GHK: https://pubchem.ncbi.nlm.nih.gov/compound/73587
• Hureau et al., Chemistry, 2011 (PMID 21780203): https://pubmed.ncbi.nlm.nih.gov/21780203/
• PubChem CID 165429100, GHK-Cu 1:1 neutral: https://pubchem.ncbi.nlm.nih.gov/compound/165429100
• PubChem CID 9831891, bisprezatide copper (2:1): https://pubchem.ncbi.nlm.nih.gov/compound/9831891
• Bian et al., Redox Biology, 2024 (PMID 38879894): https://pubmed.ncbi.nlm.nih.gov/38879894/
• J Orthop Res, 2015 (PMID 25731775): https://pubmed.ncbi.nlm.nih.gov/25731775/
• Wen et al., Biogerontology, 2026 (PMID 42084774): https://pubmed.ncbi.nlm.nih.gov/42084774/
• Pickart and Margolina, Int J Mol Sci, 2018 (PMC6073405): https://pmc.ncbi.nlm.nih.gov/articles/PMC6073405/
• Pickart et al., Oxid Med Cell Longev, 2012 (PMID 22666519): https://pubmed.ncbi.nlm.nih.gov/22666519/
• NPR, 7 September 2026: npr.org/2026/09/07/nx-s1-5955552
• FDA, bulk drug substances for compounding (current as of 22 April 2026): https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks

Cagri-Reta is a two-peptide research blend of cagrilintide and retatrutide, typically 10 mg of each per vial. The two molecules weigh within about 320 daltons of each other, yet they bind completely different receptor families, and that pairing is the whole reason the blend exists.

Cagrilintide is a long-acting amylin analog from Novo Nordisk. Retatrutide is Eli Lilly’s single-molecule agonist at three receptors. Both are lipidated peptides, both run as large molecules on an HPLC column, and both need their own identity result on a blend COA.

This guide covers each molecule’s identity and structure, its receptor targets, how to read a two-peptide COA, and where each compound stands in October 2026. Our Cagrilintide + Retatrutide 10/10 mg is the example used throughout.

What Is Cagri-Reta?

Quick answer: Cagri-Reta is a research blend that combines two separate synthetic peptides in one lyophilized vial: cagrilintide, a long-acting amylin analog, and retatrutide (LY3437943), a single peptide that binds the GIP, GLP-1, and glucagon receptors. Life Link’s version contains 10 mg of each, with its batch documents published on the product’s certificate page.

The blend travels under several names, which can make catalogues confusing:

• Cagri-Reta or Reta-Cagri: the two short forms joined, in either order.
• Reta + Cagri: the same pairing written as two parts, or as plain cagri reta without the hyphen.
• GLP-3 + cagrilintide: “GLP-3” is an informal nickname for retatrutide, coined because it reaches a third receptor. No receptor called GLP-3 exists.

Every one of these names points to the same two molecules, and the label should always state the amount of each.

The reason they’re studied together is simple. Cagrilintide works on amylin and calcitonin receptors. Retatrutide works on the incretin and glucagon receptors. Because the two sets of receptors don’t overlap, a single model can carry both signals at once, and a researcher can compare that with either compound alone.

Cagrilintide vs Retatrutide: Side-by-Side Identity Table

The table below contains the reference identity data for both compounds in one place. Every value comes from a public database or the developer’s own publication, linked below the table.

Property	Cagrilintide	Retatrutide
Developer	Novo Nordisk	Eli Lilly
Code	AM833 (also listed as NN0174-0833)	LY3437943
Class	Long-acting amylin analog	GIPR, GLP-1R and GCGR triple agonist
Length	37 amino acids	39 amino acids
Formula	C194H312N54O59S2	C221H342N46O68
Molecular weight	4409.0 g/mol	4731.34 g/mol
CAS	1415456-99-3	2381089-83-2
Key modifications	Cys2 to Cys7 disulfide bridge; C20 fatty diacid on the N-terminus through a γ-glutamic acid linker; C-terminal proline amide	Aib at positions 2 and 20; α-methyl-leucine at 13; fatty diacid side chain on Lys17 through a linker
Receptor targets	Amylin receptors AMY1, AMY2, AMY3 and the calcitonin receptor	GIP receptor, GLP-1 receptor, glucagon receptor

Sources: cagrilintide formula, weight, CAS, and structure from PubChem CID 171397054 and its design paper (Kruse et al., J Med Chem, 2021). Retatrutide formula, weight, sequence, and targets from KEGG D12430; its Lys17 acylation site from the receptor-structure study by Li et al., Cell Discovery, 2024.

Cagrilintide and retatrutide identity data side by side, with what a blend COA should show.

Two details from the table come up again on any blend COA. The weights differ by roughly 322 Da, which lets a mass spectrometer tell the two apart without trouble. And both molecules carry a fatty side chain, so both behave as greasy, slow-eluting peptides on a reverse-phase HPLC column.

What Is Cagrilintide?

Quick answer: Cagrilintide is a synthetic, long-acting analog of the hormone amylin, developed by Novo Nordisk. It is a lipidated peptide with a disulfide bridge, and it binds amylin receptors (AMY1, AMY2, and AMY3) and the calcitonin receptor. In research, it is studied as a receptor-binding and assay tool; it has no FDA approval as a standalone product.

Structure and Modifications

Cagrilintide is 37 amino acids long and starts from the amylin sequence. A disulfide bridge between Cys2 and Cys7 closes a small ring near the N-terminus, the same ring native amylin carries. The C-terminal half contains three prolines at positions 25, 28, and 29, and the chain ends in a proline amide.

The long-acting part comes from lipidation. A C20 fatty diacid is attached to the N-terminal lysine through a γ-glutamic acid linker. Novo Nordisk’s chemists described that design choice in their 2021 development paper.

Receptor Targets: AMY1-3 and the Calcitonin Receptor

Amylin receptors are built from two parts. The calcitonin receptor (CTR) pairs with one of three receptor activity-modifying proteins, RAMP1, RAMP2, or RAMP3, to form AMY1, AMY2, and AMY3. Cagrilintide activates all three as well as CTR on its own.

In cell assays, binding is usually read out as cAMP, the second messenger these receptors raise. Researchers express CTR with or without a given RAMP and compare cAMP responses across those cell lines to map a ligand’s receptor profile. A single-compound cagrilintide 5 mg vial suits that kind of side-by-side assay.

What Is Retatrutide?

Quick answer: Retatrutide (LY3437943) is a 39-amino-acid synthetic peptide developed by Eli Lilly. One molecule activates three receptors (GIPR, GLP-1R, and the glucagon receptor), which is why it is called a triple agonist. It carries a fatty-acid side chain for albumin binding. As of 31 October 2026, it is investigational and not FDA approved.

Structure: Aib Substitutions and Lipidation

Retatrutide’s sequence reads YXQGTFTSDYSILLDKKAQXAFIEYLLEGGPSSGAPPPS, where each X is Aib (α-aminoisobutyric acid). The Aib at position 2 resists cleavage by the DPP-4 enzyme, and a second Aib appears at position 20. Position 13 carries α-methyl-leucine, another non-natural residue.

The fatty diacid side chain is attached to Lys17 through a linker. That side chain lets the peptide bind albumin reversibly. Lilly’s discovery team set out the design in Cell Metabolism in 2022.

Triple Receptor Binding (GIPR / GLP-1R / GCGR) in Assay Terms

All three of retatrutide’s receptors belong to the class B GPCR family, and all three raise cAMP when activated. That makes them easy to compare in the same assay format. Researchers typically use cell lines that express a single human receptor each and measure cAMP across a range of concentrations.

Those concentration-response curves show how potent the peptide is at each receptor relative to the native hormones, GIP, GLP-1, and glucagon. Cryo-EM structures published in 2024 show how one ligand fits all three binding pockets. For single-compound work, a retatrutide 15 mg vial keeps the triple agonist on its own.

Why Are Cagrilintide and Retatrutide Researched Together?

Quick answer: Researchers pair them because they act on different receptor families: amylin/calcitonin receptors for cagrilintide, and incretin/glucagon receptors for retatrutide. This lets studies compare single-receptor and multi-receptor signaling in one model. The combination itself has so far been described only in animal work, while each molecule has its own separate research history.

The evidence comes in two clearly separate piles:

• The combination: one published study, in rats. Petersen and colleagues reported it in Nature Metabolism in October 2026, and it remains the only peer-reviewed paper on this exact pairing.
• Cagrilintide alone: its own development line at Novo Nordisk, from in vitro receptor work through a human clinical programme.
• Retatrutide alone: its own programme at Eli Lilly, from receptor pharmacology through Phase 3 human trials.

In assay terms, the pairing makes a tidy experiment. One ligand reaches receptors built from CTR and RAMPs, the other reaches three class B GPCRs, and all of them raise cAMP. That shared readout lets a researcher measure both signals the same way and see how they combine.

So a blend of the two draws on two long, separate histories and one new animal study of them together.

Blend vs Separate Vials

A cagrilintide retatrutide blend in one premixed 10/10 mg vial and two single vials hold the same molecules. They suit different study designs.

Feature	Cagri-Reta blend (one vial)	Two single vials
Consistency	Both peptides come from one mixing step, so every vial in the batch shares the same pairing	Each compound has its own batch
Documentation	One COA covers both compounds	Two COAs, one per compound
Study design	Built for work that needs both compounds together	Lets each compound run alone as well as together

Separate vials make controls easier, since a study can run cagrilintide alone, retatrutide alone, and both together from known lots. The blend keeps handling simple, with one vial and one document to track per batch. For a fuller comparison, read our guide to peptide blends vs single vials.

How to Read a Cagri-Reta COA

Quick answer: A Cagri-Reta COA should show two separate identity and purity results, one for each peptide. Look for two resolved HPLC peaks, a mass-spec match for each compound’s expected molecular weight (about 4409 and 4731 Da), the content of each per vial (10 mg + 10 mg), and a lot number matching your vial.

A single retatrutide COA has one molecule to prove. A blend report has two, and it has to show each one in the right amount.

Two HPLC Peaks and Resolution

On a single-peptide chromatogram, purity is the main peak’s share of the total area. A blend chromatogram should show two main peaks, one per compound, each with its own retention time. They need to be resolved, meaning separated down to the baseline, so each area can be measured cleanly. Two merged peaks reported as a single percentage can’t tell you how pure each component is. Both molecules carry fatty side chains and tend to elute late, so a method that separates them cleanly shows the lab tuned it for this blend.

MS Confirmation for Each Peptide

Mass spectrometry confirms that each peak is the molecule it should be. Look for two observed masses, one near 4409 Da for cagrilintide and one near 4731 Da for retatrutide, each within the lab’s stated tolerance. Large peptides often show up as several charge states, which the lab converts to a single mass. The amount of each peptide per vial comes from a separate measurement against a reference standard, reported in mg. Our guide to HPLC vs mass spectrometry explains how the two methods divide the work.

Lot, Date and Lab Checks

The paperwork checks are the same as for any peptide. Match the lot number to the vial label, confirm the test date fits the batch, and verify the report with the lab using its key or QR code. For a blend, also confirm the sample line names both compounds and both amounts, since a report for either single peptide can’t stand in for the blend. Our step-by-step guide on how to verify a peptide COA walks through all six checks.

Is Cagri-Reta FDA Approved?

Quick answer: No. As of 31 October 2026, neither the Cagri-Reta blend nor retatrutide on its own is FDA approved. Retatrutide remains investigational with Eli Lilly, and cagrilintide is in development with Novo Nordisk, including as part of CagriSema. Research blends like Cagri-Reta are sold for laboratory research use only.

Here’s the dated record behind that answer:

Date	Event	Source
Aug 2021	Novo Nordisk chemists publish cagrilintide’s design	J Med Chem
Sep 2022	Lilly scientists describe the discovery of LY3437943	Cell Metabolism
18 Dec 2025	Novo Nordisk submits a New Drug Application to the FDA for CagriSema (cagrilintide with semaglutide)	Novo Nordisk
23 Jul 2026	Lilly reports Phase 3 TRIUMPH-2 and TRIUMPH-3 results and plans a Biologics License Application for retatrutide in Q1 2027	Eli Lilly
Oct 2026	First peer-reviewed study of the cagrilintide and retatrutide combination, in rats	Nature Metabolism

Status lines change, so each one here carries a date, and this table is updated when Lilly, Novo Nordisk, or the FDA announces the next step. For the other cagrilintide pairing, see what is CagriSema.

Storage and Handling of the Lyophilized Blend

Keep the sealed vial of lyophilized powder at -20 °C, protected from light. Both peptides are large and lipidated, so the powder is best kept dry and cold until the day of the assay. Let the vial reach room temperature before opening it, so moisture doesn’t condense on the powder. The blend is soluble in water or DMSO for assay preparation. Note the batch number and the date the vial arrived, so every assay result can be traced back to its COA.

Buy Cagri-Reta 10/10 mg with a Batch COA

Our Cagri-Reta vial holds 10 mg of cagrilintide and 10 mg of retatrutide, tested through Janoshik Analytical, an independent lab that issues each report with a verification key. Identity and purity are tested on every batch, with heavy metals, endotoxin, and sterility run on a rotating cycle. To look up the batch COA, open the product, click View report, and match the batch number to your vial label.

Orders placed before 2 PM PST ship the same day from California by UPS 2-Day Air, with free shipping over $250. Every purchase is for qualified laboratory research under our research-use terms.

FAQs

What is Cagri-Reta?

Cagri-Reta pairs two synthetic peptides in one vial: cagrilintide, Novo Nordisk’s lipidated amylin analog, and retatrutide (LY3437943), Eli Lilly’s GIP, GLP-1, and glucagon receptor triple agonist. A typical vial holds 10 mg of each. It is supplied for laboratory research only.

What does “10/10 mg” mean on a Cagri-Reta vial?

Each vial contains two 10 mg portions, one of each peptide, for 20 mg of peptide in total. The first number is cagrilintide and the second is retatrutide. A blend COA should report each amount separately, so you can confirm both figures for your batch.

Is retatrutide a GLP-1 agonist?

Yes, and more. Retatrutide activates the GLP-1 receptor, the GIP receptor, and the glucagon receptor, all from one molecule. That’s why it’s called a triple agonist, and it’s the source of the informal “GLP-3” nickname. All three targets are class B GPCRs that raise cAMP in cell assays.

What is the molecular weight of cagrilintide and retatrutide?

Cagrilintide has a molecular weight of 4409.0 g/mol (C194H312N54O59S2, CAS 1415456-99-3). Retatrutide weighs 4731.34 g/mol (C221H342N46O68, CAS 2381089-83-2). The difference of about 322 Da lets mass spectrometry tell the two apart on a blend COA.

How do I verify a Cagri-Reta COA?

Match the lot number on the report to the vial label, then check the test date and the lab. Enter the report’s verification key on the lab’s own website. Finally, confirm the COA lists a separate result for each peptide, ideally two resolved HPLC peaks and two mass-spec matches.

Is Cagri-Reta FDA approved?

No. The FDA has approved neither the blend nor retatrutide by itself, and that holds at the end of October 2026. Lilly plans to file for retatrutide in Q1 2027, and Novo Nordisk filed CagriSema, which pairs cagrilintide with semaglutide, in December 2025. Cagri-Reta is sold for laboratory research use only.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

All products are supplied for in-vitro laboratory research by qualified professionals. Read the full research use disclaimer.

References

• PubChem CID 171397054, cagrilintide: https://pubchem.ncbi.nlm.nih.gov/compound/171397054
• Kruse et al., J Med Chem, 2021 (PMID 34288673): https://pubmed.ncbi.nlm.nih.gov/34288673/
• KEGG D12430, retatrutide: https://www.kegg.jp/entry/D12430
• Li et al., Cell Discovery, 2024 (PMC11255275): https://pmc.ncbi.nlm.nih.gov/articles/PMC11255275/
• Coskun et al., Cell Metabolism, 2022: https://doi.org/10.1016/j.cmet.2022.07.013
• Petersen et al., Nature Metabolism, 2026 (PMID 42744908): https://pubmed.ncbi.nlm.nih.gov/42744908/
• Novo Nordisk, CagriSema NDA submission, 18 December 2025: https://www.novonordisk-us.com/media/press-releases/novo-nordisk-cagrisema-fda-nda-submission.html
• Eli Lilly, TRIUMPH-2 and TRIUMPH-3 results, 23 July 2026: https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-successful-two-additional

Two peptide certificates can carry the same green logo, the same layout and the same 99% figure, and only one of them traces back to a real test. That report, the peptide certificate of analysis (COA), covers a single batch, and it’s the only document that ties the vial on a research bench to an identity and purity result.

This guide covers each step, plus:

• What a peptide COA contains
• How to read one line by line
• Six checks that confirm it’s real
• The signs of an edited or reused report
• What no COA can show
• A printable 10-point checklist

What Is a Peptide Certificate of Analysis?

Quick answer: A peptide certificate of analysis (COA) is a lab report for one specific batch. It shows the compound’s identity (usually by mass spectrometry), its purity (usually by HPLC), the lot number, the test date, and the lab that ran the test. A COA describes the tested sample only, which is one batch of many.

Think of it as the lab’s receipt. It records who tested what, when they tested it, and what they found. Each field answers a different question:

COA field	What it tells you
Lab name and report ID	Who ran the test, plus the unique number used to look the report up
Compound and lot	The peptide tested and the batch it came from. The lot links the report to a vial label
Test date	When the analysis ran, so it can be lined up with the batch
HPLC purity %	The share of the sample’s detected signal that comes from the target peptide
MS observed vs expected MW	Whether the measured molecular weight fits the compound’s known weight (identity)
Net peptide content	How much of the sample’s weight is peptide once water and salts are counted
Optional panels	Extra tests such as endotoxin, heavy metals or residual solvents

A report with blank fields is answering fewer of those questions, and the next section shows where each answer appears on the page.

How to Read a Peptide COA, Line by Line

Quick answer: Read a peptide COA from top to bottom. Start with the lab name, report ID, and test date. Then check the compound name and lot number, the HPLC purity percentage with its chromatogram, and the mass-spec result comparing observed to expected molecular weight. Finish with any extra panels such as net peptide content or endotoxin.

Header: Lab, Report ID, Dates

The top block tells you who did the work: the lab’s name, its contact details, and a report or task number. Most reports also carry two or three dates, usually when testing was ordered, when the sample arrived, and when the analysis ran. On our current BPC-157 report from Janoshik, the sample arrived on 17 April 2026, and the analysis ran three days later, on 20 April. All of them should come before the batch was listed for sale.

Sample Details: Compound, Lot, Quantity

Next comes the sample itself. Look for the compound name, the client, the batch or lot number, and the labelled amount, such as 10 mg. Write the lot number down, because every later check leans on it. If a label reads BPC-157 10 mg, batch 031826, the report should say the same thing, character for character.

HPLC Purity and the Chromatogram

HPLC (high-performance liquid chromatography) pushes the sample through a column and records each component as a peak on a chart called a chromatogram. Purity is reported as area %: the main peak’s area divided by the total area of every peak. A clean result shows one tall main peak at a steady retention time (the minute it leaves the column), with only small peaks beside it. A percentage printed with no chromatogram, method, or wavelength gives you much less to check, so ask for the trace. For the difference a single point makes, see what 98% vs 99% purity means.

Mass Spec: Observed vs Expected Molecular Weight

Purity tells you how much of the sample is one thing. Mass spectrometry (MS) tells you what that thing is. The instrument measures the molecule’s mass, and the report sets the observed value beside the expected molecular weight from the compound’s formula. The two should agree within the tolerance the lab states, typically within about one dalton for a peptide of this size. HPLC alone can’t confirm identity, since a different peptide could also give one clean peak. Our guide to HPLC vs mass spectrometry explains how the two methods work together.

Net Peptide Content, Water and Counter-Ions

A freeze-dried peptide sample holds more than peptide. It also carries some water and counter-ions such as acetate or TFA (trifluoroacetate) left over from synthesis and purification. Net peptide content is the share of total weight that is the peptide itself. So a sample can read 99% pure by HPLC and still contain less peptide by weight than the total weighed out. Some labs report a measured amount instead, like the 11.96 mg on our BPC-157 report for a 10 mg vial.

Optional Panels: Endotoxin, Heavy Metals, Residual Solvents

Extra panels are separate tests run on the same batch. Endotoxin testing uses the LAL method and reports bacterial endotoxin in EU (endotoxin units). Heavy metals testing, usually ICP-MS, measures elements such as lead, arsenic, cadmium, and mercury. Residual solvents testing, usually gas chromatography, measures solvent left from manufacturing. Each panel should show a measured value and the limit it was checked against, so read both.

A current Life Link Research batch COA (BPC-157 10 mg, Janoshik task #149043) with each field numbered.

How to Verify a Peptide COA Is Real: 6 Checks

Quick answer: To verify a peptide COA, check six things. The lot number matches the vial label. The test date fits the batch. The lab exists and is accredited. The report verifies on the lab’s own portal. The lab confirms the report ID when contacted. The molecular weight matches the compound’s published formula.

1. Match the Lot Number to the Vial Label

Put the vial next to the report and confirm the batch number on the label matches the lot number on the COA exactly. A COA for a different lot describes a different production run, however good its numbers look. Watch for the small mismatches as well: a missing digit, a swapped prefix, or a lot that appears on the website but nowhere on the label. A vial with no lot number gives the report nothing to attach to.

2. Check the Test Date Against the Batch

Confirm the test date falls after the batch was made and before it went on sale. A report dated well before the batch existed can’t describe it. Watch the order of the dates inside the report too. An analysis date earlier than the sample-received date, or a date in the future, calls for a question. Stock turns over, so a years-old report attached to a newly listed product deserves one as well.

3. Confirm the Lab Exists and Is Accredited (ISO/IEC 17025)

Look the lab up independently and confirm it has a working website, a physical address and contact details that match the report. Then check its accreditation. ISO/IEC 17025 is the international standard for testing laboratories, and ISO says it “enables laboratories to demonstrate that they operate competently and generate valid results” (ISO).

Accreditation comes from a recognized body, such as A2LA or ANAB in the US, and each one keeps a searchable directory of the labs it accredits. The ILAC signatory search lists recognized bodies country by country. Check the scope as well, since accreditation covers specific methods. A lab without accreditation can still produce sound data; you simply have one less outside check.

4. Use the Lab’s Verification Portal, Key or QR Code

Enter the report’s verification key, report ID or QR code on the lab’s own website and compare the record with your PDF. Many independent labs offer this, and it’s the strongest check you can run without picking up the phone. Here’s the process:

1. Find the key, QR code or report ID on the COA, often near the bottom of the page.
2. Type the lab’s web address yourself and skip any link printed inside the PDF.
3. Enter the key or scan the QR code to open the lab’s own record.
4. Compare that record with your copy: compound, lot, dates, and every result.

If the portal shows a different compound, a different number, or no record at all, the PDF you have differs from what the lab issued.

5. Email the Lab With the Report ID

When there’s no portal, or the portal result is unclear, ask the lab directly. Send the report ID, the compound name, and the lot number, attach the PDF, and ask one question: did you issue this report with these results? Use the contact details on the lab’s own website. A written yes from the lab is about as solid as verification gets.

6. Cross-Check the Numbers

Test the report against public data and against itself. Start with identity: look up the compound’s formula and molecular weight in a public database such as PubChem. BPC-157, for example, is listed as C62H98N16O22 with a molecular weight of 1419.5 g/mol (PubChem CID 9941957). The expected mass on the COA should match that reference, and the observed mass should land close to it. Then compare the chromatogram with the stated purity. A 99% result should show one dominant peak with small neighbours, while a trace crowded with large peaks fits a lower number. Finally, check that the peak areas in any results table add up to roughly 100%.

How Are Peptide COAs Faked?

Quick answer: Fake peptide COAs are usually real reports that have been edited or reused. Common signs: a changed compound name or lot number in a PDF, one chromatogram reused across products, a single COA covering many batches, copied lab logos, dates that don’t fit the batch, and PDF metadata that shows recent editing.

That’s useful to know, because an altered report still points back to an original record at the lab, and the edit rarely survives a side-by-side comparison. These are the signs to look for:

Red flag	How to check it
Edited PDF text or fonts	Zoom in on the compound name, lot and results. Mixed fonts, uneven spacing or a blurred patch around one field point to editing. Open the PDF’s document properties and look for a recent modified date or editing software
Reused chromatogram	Compare traces across a supplier’s products. Identical peak shapes, retention times and baseline noise on reports for different compounds can’t all be right
One COA for many lots	Check whether one report ID appears across several batches or products. Each batch needs its own report
Logo with no verifiable lab	Search the lab name independently. With no website, address or accreditation listing, nobody can confirm the report
Impossible dates	Look for analysis dates before sample receipt, dates in the future, or tests run before the batch existed
MW that doesn’t match the compound	Compare the expected mass with a public database entry for the compound’s formula
No report ID	Without an ID or key, the lab has nothing to look up. Ask the supplier for one

A single red flag is a reason to ask questions. Two or more, and the report is best treated as unverified until the lab confirms it.

What Can’t a COA Tell You?

Quick answer: A COA describes only the sample the lab tested on that date. It can’t prove every vial in a batch is identical, that storage after shipping was correct, or that tests missing from the report were done. Missing panels, such as endotoxin, mean that result is simply unknown.

A COA is a snapshot of one sample on one day. Here’s what falls outside that snapshot:

• Vial-to-vial consistency. The lab analysed the sample it received. Other vials from the batch share its production run, and the report speaks for the sample.
• Which vial was sent. The supplier chooses the sample, so traceability back to a lot number carries a lot of weight.
• Handling after testing. Storage temperature, transit time and shelf time all come after the report is signed.
• Tests nobody ran. A blank panel is an unknown result. If endotoxin isn’t on the report, the endotoxin level hasn’t been measured.

Our own certificate pages carry the line “Results relate only to the sample tested.” That’s the correct way to read any COA, ours included.

Third-Party vs In-House COAs: Which Should You Trust?

Quick answer: A third-party COA comes from an independent lab with no stake in the sale, so it carries more weight than an in-house report. Trust grows when the lab is named, accredited, and lets you check the report yourself. An in-house COA can still be correct; it just can’t be checked independently.

Here’s how the three common types compare:

• Third-party, verifiable. A named outside lab, a report ID or key, and a portal or inbox that confirms it. This is the strongest form of COA verified peptides can carry.
• Third-party, unverifiable. An outside lab’s name appears, but there’s no ID, key, or contact route. The independence is there; the proof of it is thinner.
• In-house. The supplier or a related lab runs the test. The analysis may be sound, and the only source confirming it is the seller.

Third party tested peptides earn the label when a reader can trace the result to the lab without help from the supplier. For a deeper comparison, read our guide to third-party vs in-house testing.

What to Do If a COA Is Missing or Fails a Check

Quick answer: If a COA is missing or fails a check, ask the supplier for the batch-specific report that matches your lot number and contact the named lab with the report ID. If neither can be confirmed, treat the material’s identity and purity as unverified and choose a supplier that publishes checkable batch COAs.

Keep the request simple. Give the supplier the product, the lot number from the label, and the check that failed, whether that’s a lot mismatch, an old date, or a key that returned nothing. A supplier with real reports usually replies quickly with the right file. Then run the lab check yourself, so the confirmation comes from the lab. Our guide on how to choose a US supplier covers the other signals to compare.

How to Look Up a Life Link Research COA by Lot Number

Every Life Link Research product page shows a “View report” link beside the purchase options. It opens that product’s certificate page, with the current certificate first and earlier lab documents, such as endotoxin reports, listed below it. To look up a batch COA, open the product, click View report, and match the batch number on the report to the one on the vial label.

Our Janoshik reports print a QR code and a unique key with the instruction to verify the test at janoshik.com/verify/, so the result can be confirmed with the lab directly. Identity and purity are tested on every batch by independent labs, Janoshik Analytical and US-based laboratories, with heavy metals, endotoxin, and sterility run on a rotating cycle. Our testing process lists each method and standard.

Peptide COA Checklist

Run these ten checks on any peptide certificate of analysis, from any supplier. Tick each one as you go; a report that clears all ten has been confirmed from several directions.

#	Check	✓
1	Lot number on the COA matches the vial label	☐
2	Compound name and amount match the label	☐
3	Test date falls after manufacture and before sale	☐
4	Lab is named, with a working website and address	☐
5	Lab holds ISO/IEC 17025 accreditation covering the method	☐
6	Report verifies on the lab’s portal, QR code or key	☐
7	Lab confirms the report ID by email (if there’s no portal)	☐
8	HPLC purity comes with a chromatogram	☐
9	MS observed mass matches the expected MW from the formula	☐
10	Optional panels show a value and a limit; missing panels noted as unknown	☐

You can take a screenshot or create a printable PDF version of this checklist for easy reference.

Multi-Compound Blends: Reading a Blend COA

A blend holds two or more peptides in one vial, so its COA has more to prove. Each component needs its own identity result, and ideally its own measured amount, because one matching mass can only speak for one molecule. Check that every compound on the label appears by name in the results, each with its own figure. Our BPC-157 + TB-500 + GHK-Cu + KPV blend COA guide walks through a four-component example field by field.

FAQs

Can peptide COAs be faked?

Yes. Most fakes are genuine reports with an edited compound name, lot number or result, or one report reused across several batches. Altered reports rarely survive verification at the source. Entering the report’s key or ID on the lab’s portal, or emailing the lab, shows whether the results match what the lab actually issued.

How do I look up a peptide COA by lot number?

Find the lot or batch number on the vial label, then open the supplier’s COA page for that product and match the number exactly. Next, take the report ID or verification key from the COA to the lab’s own website. A peptide COA lookup is complete when both the supplier and the lab agree.

What does 99% HPLC purity actually mean?

It means 99% of the total peak area in the HPLC chromatogram belongs to the main peptide peak, measured at the lab’s detection wavelength. The remaining 1% is related impurities, such as shorter or modified sequences. The figure describes the tested sample only, and it says nothing about how much peptide the vial holds by weight.

What’s the difference between purity and net peptide content?

Purity, measured by HPLC, is the share of the peptide material that is the target sequence. Net peptide content asks a different question: how much of the weighed material is peptide at all once moisture and salts are subtracted. A sample can score high on purity and lower on net content, and a complete COA reports both.

What is mass spectrometry used for on a COA?

Mass spectrometry confirms identity. It measures the molecular weight of the compound in the sample and compares that observed value with the expected weight calculated from the peptide’s formula. A close match within the lab’s stated tolerance shows the main component is the labelled peptide, something an HPLC purity figure can’t establish alone.

How recent should a peptide COA be?

The COA should come from the same batch as the vial, so its date should fall around that batch’s production and before it went on sale. The age of the report counts for less than the match. A recent report for a different lot tells you less than an older one for the right lot.

The Bottom Line

A COA earns trust when it can be checked from the outside. The lot matches the label, the lab is real and accredited, the report verifies at the source, and the HPLC and mass-spec numbers fit the compound. Those four answers say more than any purity badge on a product photo. When the paperwork lines up, every Life Link product is supplied for laboratory research with its batch report one click from the product page.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

All products are supplied for in-vitro laboratory research by qualified professionals aged 21 and over. Read the full research use disclaimer.

References

• ISO, ISO/IEC 17025 Testing and calibration laboratories: https://www.iso.org/ISO-IEC-17025-testing-and-calibration-laboratories.html
• ILAC, signatory search for recognised accreditation bodies: https://ilac.org/signatory-search/
• PubChem CID 9941957, BPC-157: https://pubchem.ncbi.nlm.nih.gov/compound/9941957

The name and the vial often disagree. PubChem resolves TB-500 to a seven-residue peptide weighing about 889 daltons, while a great many vials sold under that name hold the whole 43-residue protein at roughly 4,963. Neither source is wrong. The label simply never belonged to one molecule, and that is the first thing to settle when asking what is TB-500.

What follows covers both molecules, how the names came apart, where the published molecular weights disagree, and how a batch certificate resolves which one a given tb-500 peptide vial contains. Life Link’s own TB-500 10mg serves as the worked example.

What Is TB-500?

Quick answer: TB-500 is a vendor name, not a scientific one. It is used for either full-length thymosin beta-4, a naturally occurring 43-residue peptide, or for Ac-LKKTETQ, a synthetic 7-residue segment of it. Nothing has been reviewed by a regulator under that name, and the material is supplied purely for laboratory research.

The designation came out of supplier catalogs, not from any journal or registry. Search the primary literature for thymosin beta-4 and the papers are plentiful; search it for “TB-500” and the term barely appears outside commercial contexts. That origin explains the looseness: a catalog label carries no obligation to specify a molecule, and two sellers can apply it to materials that differ fivefold in size.

Two products ship under it today:

• Full-length thymosin beta-4. The complete 43-residue peptide, acetylated at the N-terminus.
• The Ac-LKKTETQ fragment. Seven residues taken from the middle of that sequence.

Both are legitimate research materials, and they are not interchangeable.

What Is Thymosin Beta-4?

Quick answer: Thymosin beta-4 runs to 43 amino acids, carries an acetyl group on its N-terminus, and was first isolated from thymus tissue. It is one of the most studied members of the beta-thymosin family. In biochemical assays, it binds G-actin, the monomer form of actin, which is the property most research on it starts from.

Structure

The chain is catalogued in UniProt as P62328, where the mature 43-residue peptide runs:

Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES

Three structural points govern how it behaves in a vial and on an instrument. It carries no cysteines, so there is no disulfide chemistry to preserve. Its single methionine at position 6 is the one residue that can pick up an extra 16 daltons through oxidation. And in solution the peptide is intrinsically disordered, taking on defined structure only when it binds actin, with no fixed fold of its own (Vitamins and Hormones, 2016, PMID 27450730).

What the literature covers

Published work on thymosin beta-4 is overwhelmingly cell-culture and animal-model research, with the G-actin binding interaction serving as the biochemical starting point for most of it. The beta-thymosin family is studied as a group, so papers frequently cover several members at once instead of Tβ4 alone.

TB-500 vs Thymosin Beta-4: What’s the Difference?

Quick answer: Full-length thymosin beta-4 is the whole 43-residue molecule. The “TB-500” fragment is Ac-LKKTETQ, just residues 17 to 23, at about one-fifth of the mass. Sellers use both names loosely, so a vial labelled “TB-500” can contain either. They are different molecules and give different results on a COA.

	Full-length thymosin beta-4	Ac-LKKTETQ fragment
Residues	43	7 (Tβ4 17 to 23)
Molecular weight	about 4,963 Da	about 889 Da
Monoisotopic mass	4,960.49	888.49
CAS	77591-33-4	885340-08-9
Formula	C212H350N56O78S	C38H68N10O14
PubChem	CID 45382195	CID 62707662
Origin	Naturally occurring peptide, made synthetically for research	Synthetic segment
Molecules in 10mg	2.0 µmol	11.2 µmol, about 5.6× more

Read the full sequence, and the fragment is easy to locate inside it: positions 17 to 23 spell LKKTETQ, falling just past the midpoint of the chain. That stretch is the part of the molecule most closely associated with actin binding, which is why it was isolated in the first place.

Other fragments circulate too. Ac-SDKP is residues 1 to 4, taken from the opposite end of the same sequence, and it is sold under its own name, not as TB-500.

One framing to retire: asking whether Tβ4 is “better” than TB-500 compares a molecule against a name. The useful question is which molecule a study calls for, and then which one the certificate confirms.

What Is the Molecular Weight of Thymosin Beta-4?

Quick answer: Full-length thymosin beta-4 has an average molecular weight of about 4,963 Da. Some sources list higher figures because they count a salt form or use a different calculation. The fragment Ac-LKKTETQ is about 889 Da. Always compare against the mass stated on the batch COA.

PubChem puts the free-base average at 4,963 and the monoisotopic figure at 4,960.49. Figures above those appear often enough on secondary sites to cause confusion, and there are three ordinary reasons for the spread:

• Average against monoisotopic. At this chain length, the two conventions differ by roughly 2.5 Da. Neither is wrong; they answer different questions, and a report should say which it used.
• Free base against a salt. Research material is frequently supplied as an acetate. Every acetate counter-ion adds about 60 Da to the powder, and with nine lysines in the sequence there are plenty of sites to carry them, so a salt-form figure lands well above the free-base number.
• Transcription errors. A figure copied between vendor pages without a source behind it tends to drift, which is why the arbiter is the batch document rather than a catalog.

The same logic applies to the fragment, where 889 is the free-base average. Which questions each analytical method can answer is set out in HPLC vs mass spectrometry.

How Do You Tell Which “TB-500” Is in Your Vial?

Quick answer: Read the identity line on the COA. A measured mass near 4,963 Da means full-length thymosin beta-4; a mass near 889 Da means the Ac-LKKTETQ fragment. The report should also name the molecule, give its sequence or CAS, show HPLC purity, and carry a batch number matching your vial.

What a TB-500 COA should establish: identity, purity, content and traceability

Field on the COA	What it should say
Sample name	Names the molecule, not only “TB-500”
Sequence or CAS	77591-33-4 for full-length, 885340-08-9 for the fragment
Identity result	The method used, and what it confirmed
Purity	Purity by HPLC, read from the batch result
Content	Peptide against label claim, in mg
Batch number	Matches the number printed on the vial
Lab, verification code, test date	Makes the report traceable back to the testing lab

Three red flags cover most problems: a “TB-500 99%” line with no identity result behind it, a stated mass that matches neither molecule, and a missing batch number.

How identity is actually established counts here. Mass spectrometry measures the molecule’s mass directly, which separates 4,963 from 889 beyond argument. Retention-time matching on HPLC is a different test: it compares the sample against a named reference standard and confirms they behave alike on the column. That is meaningful evidence when the reference standard is identified on the report, and it is worth knowing which of the two a certificate relied on.

Life Link’s current 10mg batch, tested by Prodigy Labs on September 29, 2026 (report PL-COA-20260929-BF19-R4), records its identity as “Thymosin beta-4 (full length, 43 aa)”, confirmed by HPLC retention-time matching against a full-length acetate reference standard. Purity is reported above 99.5% by RP-HPLC-UV, and peptide content as 9.8 mg against a 10 mg label claim. So the material is the 43-residue protein. Checking any certificate against the issuing lab is covered in how to verify a COA is real.

Why Does Price per mg Depend on Which Molecule?

Quick answer: Ten milligrams of the fragment and ten milligrams of full-length thymosin beta-4 are very different products. The full-length protein is longer and more costly to make. Compare price per milligram only between listings that contain the same molecule, confirmed on their COAs.

Synthesis cost scales with chain length. Each additional residue is another coupling step, another chance of a deletion sequence, and more purification work to remove what did not couple cleanly. A 43-residue chain is a substantially larger undertaking than a 7-residue one, and the catalog price follows.

The molecule count runs the other way, which is what makes a naive comparison misleading. The same ten milligrams delivers about 2.0 µmol of the full protein or about 11.2 µmol of the fragment. A listing that looks cheap per milligram may simply hold the shorter molecule, so the only sound comparison is between listings whose certificates name the same compound.

TB-500 in Blends and Kits

Quick answer: TB-500 is a component of several multi-peptide products: with BPC-157 (often called “Wolverine”), with BPC-157 and GHK-Cu (GLOW), and with those plus KPV (KLOW). Each blend COA should list TB-500 separately, with its own mass result.

Multi-component products raise the documentation bar rather than lowering it. A certificate covering two or four peptides has to resolve each one, which means a separate identity result per compound and a chromatogram showing a peak for each. A single combined purity figure describes none of them individually.

For TB-500 specifically, the identity question carries straight into the blend: a kit listing “TB-500 10mg” inherits the same ambiguity as a standalone vial, and only the component-level result settles it. The BPC-157 + TB-500 kit keeps each compound in its own vial with its own certificate, which makes that check straightforward. The GHK-Cu, BPC-157 and TB-500 blend guide sets out the three-component composition.

Is TB-500 Legal? FDA and WADA Status

Quick answer: No FDA approval covers thymosin beta-4 or its fragments, and research-grade material goes to laboratories only. An FDA advisory committee took TB-500 up in July 2026 as a 503A compounding candidate, with no binding effect. Thymosin beta-4 also appears on the WADA Prohibited List.

TB-500 appears on the first-day agenda of the July 23 to 24, 2026 advisory committee meeting, listed in free base and acetate forms. FDA stamps that page as current to August 6, 2026. A committee recommendation advises the agency and nothing more: a listing requires notice-and-comment rulemaking, and the 503A list concerns compounding pharmacies rather than reagent supply to laboratories. Dates and next steps are tracked in TB-500 and MOTS-c FDA status.

In sport, the WADA Prohibited List effective January 1, 2026 names the compound under section S2, among growth factors, with the entry reading “Thymosin-ß4 and its derivatives e.g. TB-500”. The wording covers both the full protein and fragments taken from it, and the prohibition applies at all times.

How Should TB-500 Be Stored?

Quick answer: Freeze-dried vials belong at -20°C, sealed, dark, and dry. Warm a vial to ambient temperature first, then open it, which keeps condensation off the powder. Record the batch number against its certificate while the box is still to hand. These are storage conditions for the dry powder only.

One sequence-specific note: with a single methionine at position 6 and no cysteines, oxidation at that one residue is the change most likely to show up on a later identity trace, as an extra 16 daltons. Keeping the vial sealed, cold, and dry is what holds the material close to the state its certificate describes.

TB-500 FAQs

Is TB-500 the same as thymosin beta-4?

Sometimes. Some sellers use TB-500 for the complete 43-residue protein, others for the 7-residue Ac-LKKTETQ fragment taken from it. Because the same label covers both, the molecule named on the batch certificate is what settles it, not the product title.

How many amino acids is TB-500?

Either 43 or 7, depending on the molecule. Full-length thymosin beta-4 runs 43 residues with an acetylated N-terminus. The fragment sold under the same name is 7 residues, Ac-LKKTETQ, corresponding to positions 17 to 23 of the full sequence.

What is Ac-LKKTETQ?

It is a seven-residue peptide matching residues 17 to 23 of thymosin beta-4, acetylated at the N-terminus. PubChem lists it as CID 62707662, CAS 885340-08-9, formula C38H68N10O14, with an average mass near 889 Da. It is the region most associated with actin binding.

What is the difference between TB-500 and BPC-157?

They are unrelated molecules. BPC-157 is a synthetic 15-residue sequence of about 1,419 Da drawn from a gastric protein. TB-500 refers to thymosin beta-4 or its fragment, from an entirely different protein family. Our comparison of BPC-157 vs TB-500 covers both.

Which TB-500 does Life Link sell?

The full-length molecule. The current 10mg batch certificate, issued September 29, 2026, records identity as thymosin beta-4 at full length, 43 amino acids, with purity above 99.5% by HPLC and peptide content of 9.8 mg against the 10 mg label claim.

Why do molecular weights differ between websites?

Three reasons account for most of it: average mass against monoisotopic mass, which differ by roughly 2.5 Da here; free base against an acetate salt, where each counter-ion adds about 60 Da; and figures copied between pages without a primary source. The batch document settles it.

⏱ TB-500 in 30 seconds

TB-500 is a catalog name covering two molecules. One is thymosin beta-4 itself: 43 residues, acetylated, about 4,963 Da, CAS 77591-33-4. The other is Ac-LKKTETQ, seven residues from positions 17 to 23 of that sequence, about 889 Da. Ten milligrams of the fragment contains roughly 5.6 times as many molecules. The identity result on the batch certificate is what tells the two apart.

For Research Use Only. Not for use in diagnostic or therapeutic procedures. Read our full Research Use Disclaimer.

What is described above is a laboratory reagent for qualified researchers aged 21 and over. The Terms and Conditions carry the conditions of sale in full.

References

• PubChem CID 45382195, thymosin beta-4: https://pubchem.ncbi.nlm.nih.gov/compound/45382195
• PubChem CID 62707662, TB-500 (Ac-LKKTETQ): https://pubchem.ncbi.nlm.nih.gov/compound/62707662
• UniProt P62328, thymosin beta-4 (human), 43-residue chain: https://www.uniprot.org/uniprotkb/P62328/entry
• Vitamins and Hormones, 2016, actin-induced structure in the beta-thymosin family. PMID 27450730: https://pubmed.ncbi.nlm.nih.gov/27450730/
• FDA, Pharmacy Compounding Advisory Committee meeting, July 23 to 24, 2026: https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
• WADA Prohibited List 2026, effective January 1, 2026: https://www.wada-ama.org/en/prohibited-list

Two vials can both read “TB-500 10mg” and hold molecules that differ more than fivefold in mass. One is thymosin beta-4, a 43-residue protein near 4,963 Da. The other is Ac-LKKTETQ, a seven-residue fragment near 889 Da. Same label, same milligrams, very different contents, and the wolverine blend is where that ambiguity turns up most often, because the name travels further than any specification sheet.

What follows covers the composition of a wolverine peptide combination, the formats it ships in, how to read a two-component certificate, and what US supply looks like. Life Link’s own two-vial BPC-157 + TB-500 kit is used as the worked example throughout.

What Is the Wolverine Blend?

Quick answer: Wolverine is the catalog name given to BPC-157 and TB-500 when they are sold as a pair, most often at 10mg each. The nickname belongs to nobody, and no regulator has assessed anything bearing it. Labels vary between sellers, so the contents line and the batch certificate are the parts that actually describe the material.

The nickname came from supplier catalogs and forum shorthand, not from any laboratory or registry. Nobody holds a trademark on it, which is exactly why two listings under the same name can hold different material.

Three formats share the label:

• Blend (one vial). Both peptides freeze-dried together in a single vial at a fixed ratio.
• Kit (separate vials). Each peptide in its own vial, boxed together. Kit is the accurate word for this format, since nothing is actually combined.
• Capsules. An oral format, outside the scope of this guide.

Throughout the rest of this guide, the combination is called a BPC-157 + TB-500 blend, because that names what is in the vial.

What Is in the Wolverine Blend?

Quick answer: A standard Wolverine blend contains BPC-157 (10mg) and TB-500 (10mg), 20mg in total. BPC-157 is a synthetic 15-residue peptide; TB-500 is either full-length thymosin beta-4 or a short fragment of it, depending on the supplier.

Every value below was read from PubChem and UniProt on October 25, 2026.

Component	Amount	Type	Sequence / size	Molecular weight	CAS
BPC-157	10 mg	Synthetic 15-residue peptide	GEPPPGKPADDAGLV	~1,419.5 g/mol (CID 9941957)	137525-51-0
TB-500 (full-length)	10 mg	Thymosin beta-4, 43 residues, N-acetylated	SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES (UniProt P62328)	~4,963 g/mol (CID 45382195)	77591-33-4
TB-500 (fragment)	10 mg	Ac-LKKTETQ, a 7-residue fragment	LKKTETQ, acetylated	~889 g/mol (CID 62707662)	885340-08-9

The BPC-157 row is settled: one sequence, one mass, one CAS number. The TB-500 rows are the reason this table has three entries instead of two.

Which “TB-500” Is in Your Vial?

Quick answer: Sellers use “TB-500” for two different molecules: full-length thymosin beta-4 (43 residues, about 4,963 Da) and a 7-residue fragment, Ac-LKKTETQ (about 889 Da). Both can be labelled “TB-500 10mg”. The COA’s measured mass tells you which one you bought.

PubChem keeps them as separate records, and the names on those records are the clearest evidence that the field uses one label for two compounds. Search “TB-500” and you land on the 889 Da fragment. Search “thymosin beta-4” and you land on the 4,963 Da protein. Both are legitimate entries, and catalogs borrow freely from each.

The arithmetic is where it lands:

Molecule	Mass	Molecules per 10 mg (approximate)
Thymosin beta-4, 43 residues	~4,963 Da	2.0 µmol
Ac-LKKTETQ, 7 residues	~889 Da	11.2 µmol

Ten milligrams of the fragment delivers roughly 5.6 times as many molecules as ten milligrams of the full protein. Two listings at the same price per milligram are not comparable until you know which molecule each one holds.

Two molecules sold as TB-500: thymosin beta-4 at 43 residues and the Ac-LKKTETQ fragment at 7 residues

How to check: read the observed mass on the mass-spectrometry line of the batch COA. A result near 4,963 is the full protein; a result near 889 is the fragment. The product name on the label settles nothing on its own.

Life Link’s TB-500 10mg is listed as full-length thymosin beta-4, CAS 77591-33-4, at 4,963.55 Da, and that CAS number and mass both correspond to the 43-residue protein. Confirm it against the mass on the current batch report before relying on it.

Blended Vial vs Two-Vial Kit: Which Format?

Quick answer: A blended vial holds both peptides freeze-dried together at a fixed 1:1 ratio, with one COA covering both. A two-vial kit keeps each peptide in its own vial with its own COA, so each can be checked separately and the ratio is set by the study, not the vial.

Factor	One blended vial	Two-vial kit
Verification	One COA that must name both compounds	One COA per compound
Ratio	Fixed at 1:1	Set by the study design
Stability questions	Two peptides stored together	Each stored apart
Price per mg	Usually lower	Usually higher

The verification row is the one that separates the formats in practice. A single report covering a blended vial has to carry two identity results and two purity results, and plenty of them do not. With separate vials, each report is an ordinary single-compound certificate, which is far easier to check and far harder to fudge.

The ratio row cuts the other way. A blended vial fixes the proportion at the point of manufacture, so a design calling for anything other than 1:1 cannot use it. Separate vials leave that choice open.

Life Link stocks both: the BPC-157 + TB-500 10/10mg blended vial at $160, and the two-vial kit at $223.25. For the general case, blends vs single vials covers the trade-off across the catalog.

What Should a Wolverine Blend COA Show?

Quick answer: A blend COA should list BPC-157 and TB-500 separately, each with its own identity result by mass spectrometry and its own purity result by HPLC. Expect two peaks on the chromatogram, not one. A single “Wolverine 99%” line doesn’t show that both compounds are present, or in what amount.

What to look for	Why it belongs there
Both compound names printed separately	A combined name hides which component was measured
Two mass results	~1,419 for BPC-157, plus ~4,963 or ~889 for TB-500
A purity figure for each	Purity by HPLC, read per compound, not as one number
Two peaks on the chromatogram	One peak cannot represent two molecules of different mass
Batch number matching the vial	Ties the document to the material in hand
Lab name, verification code, and test date	Lets the report be checked at source

What a BPC-157 and TB-500 blend COA should show, with two peaks on the chromatogram

Red flags are the mirror image: one combined percentage, no masses, no batch number, no lab name.

For a blended vial, the chromatogram is the quickest read. Two compounds at a 5.6-fold or 3.5-fold mass difference separate cleanly on a reverse-phase column, so a single peak on a two-component product is a question worth asking before purchase, not after. Our guides on how to verify a COA is real, and HPLC vs mass spectrometry cover the mechanics of each check.

How Do BPC-157 and TB-500 Differ as Molecules?

Quick answer: BPC-157 is a 15-residue synthetic sequence of about 1,419 Da. TB-500 is one of two things: thymosin beta-4 itself at 43 residues and roughly 4,963 Da, or the seven-residue piece cut from it. They differ in size, origin, and how they are characterised on a COA, which is why each needs its own result.

BPC-157 runs fifteen residues, GEPPPGKPADDAGLV, and its sequence was taken from a larger protein identified in gastric juice. Nothing about it is extracted; the chain is assembled by solid-phase synthesis.

Thymosin beta-4 is a naturally occurring 43-residue protein, catalogued in UniProt as P62328 and N-acetylated at its N-terminus. The LKKTETQ stretch inside it, residues 17 to 23, is the part the short fragment reproduces.

That size difference has a consequence for the “1:1” shorthand. Equal milligrams are not equal molecules. Ten milligrams of BPC-157 is about 7.0 µmol, while ten milligrams of the 43-residue protein is about 2.0 µmol, so a 1:1 blend by mass is closer to 3.5:1 by molar amount. Against the short fragment the same 10mg pairing runs the other way, nearer 1:1.6. A protocol that specifies molar amounts needs the arithmetic done from the mass on the certificate.

Published work on both compounds is mostly rodent and cell-culture studies. A fuller treatment of both molecules is in BPC-157 vs TB-500 compared.

Is the Wolverine Blend Legal or FDA Approved?

Quick answer: No FDA approval exists for BPC-157 or for TB-500, and nothing has ever been reviewed under the name “Wolverine”. In the US, both are supplied as research reagents for laboratory use. An FDA advisory committee took up both compounds in July 2026 for the 503A compounding list, and its recommendation carries no legal force.

The FDA’s calendar entry for the July 23 to 24, 2026 advisory committee meeting names BPC-157 and TB-500 on the first day’s agenda, each listed in free base and acetate forms. The page is marked current as of August 6, 2026. That committee only advises. Anything reaching the 503A list has to clear notice-and-comment rulemaking first, and the list itself governs compounding pharmacies, not the supply of reagents to laboratories. BPC-157’s legal status tracks where that stands.

In sport, both appear on the WADA Prohibited List effective January 1, 2026, in separate sections. The list places BPC-157 in S0, the non-approved substances class, while TB-500 falls under S2, where the entry reads “Thymosin-ß4 and its derivatives e.g. TB-500”. Both carry a ban that applies year-round.

How Should the Wolverine Blend Be Stored?

Quick answer: Keep the sealed freeze-dried vials in a -20°C freezer, shielded from light and kept dry. Bring a vial up to room temperature before breaking the seal, so moisture does not condense inside. Keep each kit vial labelled with its batch number next to its COA.

With a two-vial kit, there is a small record-keeping point: the vials carry different batch numbers and arrive with different certificates. Log them separately on receipt, because once the box is discarded, matching a vial back to its report depends entirely on the label.

Where to Buy the Wolverine Blend in the US

Quick answer: Choose a US supplier that names both compounds on the label, publishes a separate identity and purity result for each, ships from US stock, and sells for research use only. Compare price per verified milligram, and check which TB-500 molecule each listing contains.

Four checks separate a documented listing from a name on a box:

• Both compounds named, with amounts, on the product page itself.
• A batch COA for each compound, published and linked, with the lab named.
• Which TB-500 molecule the listing contains, stated or evident from the mass.
• US stock and research-use-only terms at checkout.

Life Link supplies the combination as a two-vial kit: BPC-157 10mg and TB-500 10mg in separate vials, each with its own certificate, dispatched same day on orders placed before 2 PM PST and shipped UPS 2-Day Air from California. The blended 10/10mg vial is the alternative where a fixed 1:1 ratio suits the work. How to choose a US peptide supplier sets out the wider checklist.

Wolverine Blend FAQs

Why is it called “Wolverine”?

The name spread through supplier catalogs and forum threads; it was never registered as a product. Since no business holds it and no agency has assessed anything carrying it, the contents line on the label and the batch COA describe a purchase far better than the nickname can.

What ratio is the Wolverine blend?

Usually 1:1 by mass: 10mg of BPC-157 and 10mg of TB-500, 20mg in total. That ratio is fixed in a blended vial. In a two-vial kit the amounts are the same, but each compound stays separate, so the proportion used is set by the study rather than by the manufacturer.

Is Wolverine the same as GLOW or KLOW?

No. The Wolverine combination holds two compounds. GLOW adds GHK-Cu to the same pair, making three, and KLOW adds both GHK-Cu and KPV, making four. The naming is catalog convention rather than chemistry, so check each listing’s composition. Our guide to the GLOW blend sets out that composition.

Can I buy BPC-157 and TB-500 separately?

Yes. Both are sold as single-compound vials, each with its own batch certificate, and buying them separately is what a two-vial kit amounts to. BPC-157 10mg is listed on its own at $89, with TB-500 10mg listed separately at $146.

What is the difference between a blend and a kit?

A blend is one vial holding both peptides freeze-dried together, documented by a single COA that has to cover both. A kit is two vials, each with its own COA. The blend fixes the ratio; the kit keeps the compounds and their paperwork separate.

⏱ Wolverine blend in 30 seconds

Two research peptides sold under one nickname: BPC-157 at 10mg and TB-500 at 10mg, 20mg total in a 1:1 ratio. It ships either as a single blended vial or as a two-vial kit. The label “TB-500” covers two different molecules, near 4,963 Da and near 889 Da, so the mass on the batch COA identifies what is actually in the vial.

For Research Use Only. Not for use in diagnostic or therapeutic procedures. Read our full Research Use Disclaimer.

Everything described above is a laboratory reagent, sold only to qualified researchers aged 21 and over. Full sale conditions appear in the Terms and Conditions.

References

• PubChem CID 9941957, BPC-157: https://pubchem.ncbi.nlm.nih.gov/compound/9941957
• PubChem CID 45382195, thymosin beta-4: https://pubchem.ncbi.nlm.nih.gov/compound/45382195
• PubChem CID 62707662, TB-500 (Ac-LKKTETQ): https://pubchem.ncbi.nlm.nih.gov/compound/62707662
• UniProt P62328, thymosin beta-4 (human), 43-residue chain: https://www.uniprot.org/uniprotkb/P62328/entry
• FDA, Pharmacy Compounding Advisory Committee meeting, July 23 to 24, 2026: https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
• WADA Prohibited List 2026, effective January 1, 2026: https://www.wada-ama.org/en/prohibited-list

Ribosomal RNA genes aren’t supposed to make proteins. Their RNA becomes part of the ribosome itself, so finding a peptide recipe tucked inside one surprised a lot of people. MOTS-c is that peptide, and it gives labs a short, fully defined molecule for studying how mitochondria send signals to the nucleus and cytoplasm. SLU-PP-332, a small-molecule ERR agonist, is another reference compound used in mitochondrial-signaling research. For a lab that wants a MOTS-c peptide with clean identity data, the structure is the place to start. New to peptide chemistry? Research peptides explained covers the basics.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

By Tyler Morgan · Scientific review by Kristen Doyle, PhD (biochemistry) · Updated October 18, 2026

What Is MOTS-c?

Quick answer: A 16-residue signaling peptide encoded in mitochondrial DNA, MOTS-c belongs to a small group called mitochondrial-derived peptides. A University of Southern California team, with Changhan Lee as first author and Pinchas Cohen as senior author, reported it in Cell Metabolism in 2015 (in vitro and mouse work). It’s made today by solid-phase synthesis.

The 2015 paper (Cell Metabolism, 2015) described a short coding sequence (sORF) within the 12S rRNA gene and showed, in cell and mouse models, that its peptide acts on “the folate cycle and its tethered de novo purine biosynthesis, leading to AMPK activation.” That pathway language is still how the field describes MOTS-c today. Our research library covers related peptides in the same style.

What does MOTS-c stand for?

The name is a compressed description of where the peptide comes from: Mitochondrial Open reading frame of the Twelve S rRNA, type c. UniProt lists the same expansion, with the gene name MT-RNR1, and a 2023 review in Antioxidants spells it out in full as “Mitochondrial open reading frame of the 12S rRNA type-c” (review, 2023).

Mitochondrial-derived peptides: humanin, SHLPs and MOTS-c

MOTS-c has two better-known relatives. Together they form a family defined by origin, not by shared sequence.

Peptide	Length	Gene region	First reported
Humanin	24 residues	16S rRNA (MT-RNR2)	2001
SHLP1 to SHLP6	20 to 38 residues	16S rRNA (MT-RNR2)	2016 (Cobb et al., in vitro and animal)
MOTS-c	16 residues	12S rRNA (MT-RNR1)	2015

Of the three, only MOTS-c maps to the 12S region, and it’s also the shortest.

What Is the Structure of MOTS-c?

Quick answer: MOTS-c is an unbranched chain of 16 residues with the sequence MRWQEMGYIFYPRKLR. Its formula is C101H152N28O22S2, with an average molecular weight near 2174.6 Da. It carries two methionines, one tryptophan, two tyrosines and a run of basic residues near the C-terminus.

Each row was cross-checked on October 18, 2026 with PubChem CID 146675088, UniProt A0A0C5B5G6 and the FDA GSRS record.

Field	Value
Sequence (one-letter)	MRWQEMGYIFYPRKLR
Sequence (three-letter)	Met-Arg-Trp-Gln-Glu-Met-Gly-Tyr-Ile-Phe-Tyr-Pro-Arg-Lys-Leu-Arg
Length	16 amino acids
Molecular formula	C101H152N28O22S2
Average molecular weight	2174.6 Da
Monoisotopic mass	2173.1077 Da
UniProt ID	A0A0C5B5G6 (MOTSC_HUMAN)
CAS	1627580-64-6
FDA UNII	A5CV6JFB78
Gene origin	MT-RNR1 (12S rRNA), mitochondrial DNA
Form	Lyophilized powder

Reading the sequence

Walk along the chain and three features jump out:

• Two methionines (M1 and M6). Both carry sulfur, the “S2” in the formula, and both can oxidize. Each oxidation adds 16 Da, a change a mass spectrum picks up easily.
• An aromatic core (W3, Y8, F10, Y11). These residues give MOTS-c strong UV absorbance at 280 nm, which helps on an HPLC trace.
• A basic tail (R13, K14, R16). Add R2 and the N-terminal amine, and the peptide carries about five positive charges against one acidic glutamate (E5) and the C-terminal acid. At neutral pH that leaves a net charge near +3.

That charge profile explains why MOTS-c shows up mostly as 3+ and 4+ ions in electrospray mass spectrometry, a point the COA section comes back to.

Each MOTS-c residue, with a hydrophobic Ile-Phe core, a charged Arg-Lys tail and a GRAVY score of -0.94

Gene origin: a peptide encoded in mitochondrial DNA

Human mitochondria carry their own small circular genome of about 16.6 kb. Most of it encodes respiratory-chain subunits, transfer RNAs and the two ribosomal RNAs. MOTS-c’s coding stretch overlaps the 12S rRNA gene, so the same stretch of DNA serves two purposes. Kim and colleagues later described this arrangement as evidence “that mitonuclear communication is genetically integrated” (Cell Metabolism, 2018).

16,569 bp human mitochondrial genome highlighting the 12S rRNA gene (MT-RNR1, 648 to 1,601), home of MOTS-c, and the 16S rRNA gene (MT-RNR2, 1,671 to 3,229), home of humanin and SHLP1-6

Handling properties for the lab

• Storage: −20 °C, desiccated, in the sealed vial.
• Solubility: soluble in water for assay preparation.
• Watch points: methionine oxidation and moisture uptake are the main ways a dry sample drifts from its original COA.

How Is MOTS-c Used in Research?

Quick answer: MOTS-c is studied in in vitro and rodent models as a tool for AMPK pathway signaling, folate-cycle and AICAR assays, and nuclear translocation studies. Human data are limited to observational measurements and registered studies, so each finding needs its model type attached before it’s compared with anything else.

AMPK and folate-cycle signaling

The 2015 paper placed MOTS-c upstream of AMPK through the folate cycle. In that model (cell lines and mice), MOTS-c slowed folate-cycle flux, which let AICAR, an intermediate in de novo purine synthesis, build up. AICAR is a known AMPK activator, so a typical assay pairs AICAR measurement with AMPK phosphorylation at Thr172 by western blot. Many labs add a second read-out downstream, phosphorylation of the AMPK substrate acetyl-CoA carboxylase (ACC) at Ser79, to confirm the pathway is engaged and not just the kinase itself.

Nuclear translocation and gene-expression studies

Three years later, the same lab showed in cultured cells that MOTS-c moves into the nucleus under glucose restriction, in an AMPK-dependent manner. There it regulated genes carrying antioxidant response elements (ARE) and interacted with the transcription factor NRF2 (in vitro, Cell Metabolism, 2018). These experiments rely on cell fractionation, imaging of tagged peptide and transcript profiling.

Study types at a glance

Model	What is measured	Source
Cell lines (in vitro)	Folate-cycle metabolites, AICAR levels, AMPK phosphorylation by western blot	Cell Metabolism, 2015
Cell lines (in vitro)	Nuclear vs cytoplasmic peptide, ARE-gene transcript levels, NRF2 binding	Cell Metabolism, 2018
Rodent	Pathway markers in tissue samples by western blot	Cell Metabolism, 2015
Human, observational	Circulating peptide quantified by ELISA	Clinical Endocrinology, 2019; Experimental Physiology, 2026
Human, registered study	NCT07505745: Phase 2, interventional, recruiting since February 2026	ClinicalTrials.gov, checked October 18, 2026

What the research does not establish

No regulator has approved MOTS-c for any human use. Results from cell lines and rodents describe how a pathway behaves in that model, and they don’t carry over to people by default. The single registered human study is still recruiting, with no posted results as of October 2026. Observational studies, for their part, measure how much MOTS-c peptide circulates; they don’t test what it does. Keeping those categories apart is the simplest way to read the literature accurately.

Is MOTS-c FDA Approved?

Quick answer: Not as of October 18, 2026. There’s no FDA-approved MOTS-c product, and openFDA’s Drugs@FDA database returns no record for it. US suppliers offer it only as a lab research reagent. A compounding vote in July 2026 left its approval status unchanged.

Each line below is dated and sourced:

• Compounding review. On July 23 and 24, 2026, MOTS-c came before FDA’s Pharmacy Compounding Advisory Committee as a 503A Bulks List candidate, and the panel voted 7 for, 5 against, with 2 abstentions, to recommend it (source: FDA meeting page, July 2026).
• Status after the vote. The committee advises FDA. A listing still needs notice-and-comment rulemaking, so MOTS-c’s 503A category is unchanged as of October 2026 (source: Federal Register, April 16, 2026).
• WADA. The 2026 Prohibited List, effective January 1, 2026, names MOTS-c under S4 (hormone and metabolic modulators) as an example of an AMPK activator, alongside AICAR (source: WADA Prohibited List, 2026).

For the full timeline and what happens next, read MOTS-c and TB-500 FDA status (2026), and for the other six peptides on that agenda, see FDA’s July 2026 peptide review.

How Is MOTS-c Supplied for Research in the US?

Quick answer: Research MOTS-c in the US typically comes as a 10 mg lyophilized vial with a lot number that links to its batch COA. Life Link ships from California and sells only under research-use-only terms to researchers aged 21 or older, so each order arrives documented and traceable to a tested lot.

What arrives and how to store it on receipt

The MOTS-c 10 mg research peptide arrives as a sealed vial in plain outer packaging. On receipt:

1. Check the seal and compare the vial’s lot number with its COA.
2. Move it to −20 °C, dry and dark.
3. Log the lot, receipt date and freezer location.

The dry, freeze-dried format is deliberate. With two methionines in the sequence, MOTS-c is more exposed to oxidation than many short peptides, and removing water slows that chemistry. A sealed, cold, dark vial keeps the sample close to the state its COA describes.

Ordering terms and US shipping

Same-day dispatch applies to orders in by 2 PM PST, sent UPS 2-Day Air out of California, with tracking by email. Every sale carries research-use-only terms, and buyers confirm they’re 21 or older. Carrier options and timings are set out in the US shipping policy.

What Should a MOTS-c COA Show?

Quick answer: A MOTS-c COA should show HPLC purity with its chromatogram, a mass-spectrometry identity result matching about 2174.6 Da, net peptide content, and the lot number, test date and testing lab. Purity by HPLC, see the batch result. Everything on the report should trace to the lot on your vial.

Test	What it confirms	What to check
HPLC purity	Share of UV signal in the main peak	A chromatogram is attached, not just a number
MS identity	The molecule is MOTS-c	Charge-state ions near 1088.06 (2+), 725.71 (3+) and 544.28 (4+), or a deconvoluted mass near 2173.1 Da
Net peptide content	Peptide vs counter-ions and water	Stated as a percentage; with five basic sites, counter-ions can make up a large share of the powder
Counter-ion	Salt form (acetate or TFA)	Named on the report; TFA often carries over from synthesis unless the batch was exchanged to acetate
Lot, date, lab	Traceability	Matches your vial; lab named; date close to manufacture

The charge-state values above are calculated from PubChem’s monoisotopic mass. A peak 16 Da heavier on any of them points to oxidized methionine. Every Life Link lot is listed in the batch COA library.

Red flags on a peptide COA

• The lot number is missing or differs from the vial.
• Purity appears as a bare number.
• The reported mass fits neither 2174.6 Da nor a known charge state.
• One report is reused across several lots.
• No lab name or test date appears.

Our guide on how to verify a peptide COA walks through each check.

MOTS-c FAQs

How many amino acids are in MOTS-c?

MOTS-c has 16 amino acids: MRWQEMGYIFYPRKLR. That’s short enough to make by solid-phase synthesis in one run, and long enough that electrospray tends to show it carrying several charges at once. UniProt lists it as MOTSC_HUMAN (A0A0C5B5G6), encoded within the mitochondrial MT-RNR1 gene.

Who discovered MOTS-c?

A University of Southern California group led by Changhan Lee, with senior author Pinchas Cohen, reported MOTS-c in Cell Metabolism in March 2015. Their work combined cell-line experiments and mouse models. Lee’s lab followed up in 2018 with the nuclear translocation study, also in Cell Metabolism and also in cultured cells.

Is MOTS-c on the WADA Prohibited List?

Yes. WADA’s 2026 Prohibited List, in force since January 1, 2026, names MOTS-c under section S4, hormone and metabolic modulators, as an example of an activator of AMP-activated protein kinase (AMPK). It appears there alongside AICAR.

Is MOTS-c the same as humanin?

No. Both are mitochondrial-derived peptides, but they’re different molecules from different genes. Humanin has 24 residues and comes from the 16S rRNA region (MT-RNR2). MOTS-c is 16 residues long and traces to the 12S region (MT-RNR1). Their sequences don’t overlap, so their mass-spectrometry identities are entirely distinct.

Does Life Link publish a COA for every MOTS-c batch?

Yes. Each lot goes to Janoshik Analytical or a US-based lab for two checks, LC-MS for identity and RP-HPLC for purity, and its report carries the batch number and test date. A wider panel (heavy metals, endotoxin, sterility) runs on rotation. See our testing process.

Closing Notes

MOTS-c is a compact, well-mapped peptide: 16 residues, one mitochondrial gene and a pathway literature built mostly on cell and rodent models. For lab work, the identity data on its COA count for more than any label. Product details and the current batch report are on the MOTS-c product page linked above.

Lab use only. For Research Use Only. Not for use in diagnostic or therapeutic procedures. MOTS-c from Life Link Research is sold to professionals as a laboratory reagent. FDA has not reviewed or approved it, and this article offers no medical advice. See our Terms and Conditions for the conditions of sale. Read our full Research Use Disclaimer. Last updated October 18, 2026.

References

Access date for every source: October 18, 2026.

• Lee C, et al. Cell Metabolism. 2015;21(3):443-454. In vitro and mouse study. doi:10.1016/j.cmet.2015.02.009
• Kim KH, et al. The mitochondrial-encoded peptide MOTS-c translocates to the nucleus to regulate nuclear gene expression in response to metabolic stress. Cell Metabolism. 2018;28(3):516-524. In vitro. doi:10.1016/j.cmet.2018.06.008
• Cobb LJ, et al. 2016;8(4):796-809. In vitro and animal study. doi:10.18632/aging.100943
• PubChem CID 146675088; UniProt A0A0C5B5G6; FDA GSRS UNII A5CV6JFB78
• ClinicalTrials.gov NCT07505745
• FDA Pharmacy Compounding Advisory Committee, July 23 and 24, 2026
• WADA Prohibited List, 2026 edition

DSIP is a synthetic nine-residue peptide, WAGGDASGE, listed under the international name Emideltide. On July 24, 2026, it drew the narrowest vote of an FDA advisory meeting on compounding peptides, and the agency’s briefing pointed less at biology than at chemistry: how well the molecule is characterized and which impurities might travel with it.

Those are lab questions, and this page answers them in the same spirit. You’ll find the sequence and identifiers, the kinds of assays DSIP turns up in, how to read its certificate of analysis, how sealed vials are stored, its US status and what to ask a supplier. More reference pages are in our research library.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

What Is DSIP?

Quick answer: DSIP is a linear nonapeptide with the sequence WAGGDASGE, also listed as Emideltide. It was first isolated from rabbit cerebral venous blood in the 1970s by a Basel group. Today it’s made by chemical synthesis and supplied as a lyophilized research peptide for analytical and in vitro work, under research-use-only rules.

The Basel lab of Guido Schoenenberger and Marcel Monnier spent years on the fraction before its sequence appeared. The final isolation and characterization were published in 1977, in Pflügers Archiv (animal tissue source, 1977) and in PNAS (1977). The Pflügers Archiv paper was part X of a series, which explains why some sites quote earlier dates for the “discovery.” The 1977 papers are the ones that put the nine residues on record.

Two things changed after that:

• Synthesis replaced extraction. Once the sequence was known, chemists could build it residue by residue on solid-phase resin. The same group compared native and synthetic material in Experientia that April (1977). Every DSIP peptide vial sold for research today is synthetic.
• The molecule got an INN. “Emideltide” is the international nonproprietary name, and it’s the term FDA uses in its compounding documents. Same peptide, two names, so search both when you check a source.

A 2006 mini-review by Vladimir Kovalzon and Tatyana Strekalova in the Journal of Neurochemistry noted that “DSIP structure is different from any other known representative of the various peptide families” (review, 2006). That uniqueness is part of why analysts treat it as a clean test case: there’s no close natural cousin to confuse it with.

Where the name comes from

DSIP’s name is a historical label. The Basel team named the peptide after the experimental system in which they first tracked the fraction, and the label stuck long before anyone could explain what the molecule does. It’s nomenclature, the way “secretin” or “substance P” reflect the labs that coined them. It isn’t a confirmed description of a property.

That’s also why you’ll see the full phrase, delta sleep inducing peptide, in older indexes and catalogs, while newer regulatory papers default to Emideltide. Kovalzon and Strekalova’s review points out that no gene, precursor protein or receptor for DSIP had been isolated as of 2006, so the name still points back to its origin rather than to a mapped pathway. For anyone searching the literature, use all three terms: DSIP, delta sleep-inducing peptide and Emideltide.

What Is the Structure of DSIP?

Quick answer: DSIP is a 9-amino-acid linear peptide: Trp-Ala-Gly-Gly-Asp-Ala-Ser-Gly-Glu. Its formula is C35H48N10O15, its molecular weight is about 848.8 g/mol, its CAS number is 62568-57-4 and its PubChem CID is 68816. It ends in an unblocked amine at one terminus and an unblocked carboxylic acid at the other, and it’s supplied as a white lyophilized powder.

Amino acid sequence

Three glycines and two alanines give DSIP a small, flexible backbone. Tryptophan at position 1 is the only aromatic residue and the only one with strong absorbance at 280 nm, which turns out to be useful on an HPLC trace.

Position	Three-letter	One-letter	Side-chain class
1	Trp	W	Aromatic, hydrophobic
2	Ala	A	Small, nonpolar
3	Gly	G	No side chain
4	Gly	G	No side chain
5	Asp	D	Acidic
6	Ala	A	Small, nonpolar
7	Ser	S	Polar, hydroxyl
8	Gly	G	No side chain
9	Glu	E	Acidic

Count the charges and a pattern appears. Asp5, Glu9 and the C-terminal carboxyl are all acidic, while the N-terminal amine is the only basic group. At neutral pH, DSIP works out to a net charge near −2, which is unusual among research peptides. On a reversed-phase column it elutes early, and in mass spectrometry it ionizes well in negative mode, a detail the COA section returns to.

Physicochemical properties

All values below were checked against PubChem CID 68816 and FDA GSRS on October 18, 2026.

Property	Value
Molecular formula	C35H48N10O15
Average molecular weight	848.8 g/mol
Monoisotopic mass	848.3301 Da
CAS number	62568-57-4
PubChem CID	68816
FDA UNII	YN28Z5YZ73 (Emideltide)
Computed XLogP	−7.1 (strongly hydrophilic)
Appearance	White lyophilized powder
Solubility	Soluble in water for assay preparation

Purity is left out of this table on purpose: it belongs to a batch, and each lot gets its own figure. Our explainer on peptide purity 98% vs 99% shows what that last percentage point represents.

Phosphorylated and analog forms in the literature

DSIP has a phosphorylated relative. Adding a phosphate to Ser7 gives P-DSIP, which raises the average mass by about 80 Da to roughly 928.8 g/mol. It has been prepared synthetically and appears in recent animal research (Life Sciences, 2018).

Researchers have also built structural analogs with substituted residues. The 2006 review notes a naturally occurring decapeptide that matches DSIP at five of nine positions. GSRS separately registers N-acetyl Emideltide (UNII CL985USD2K), a reminder to confirm which form a document describes.

How Is DSIP Used in Research?

Quick answer: In labs, DSIP is used as a reference standard in HPLC and LC-MS method development, in peptide stability and enzymatic degradation assays, and in immunoassays for DSIP-like immunoreactivity in tissue extracts. Researchers should note which findings come from in vitro work, which from animal models, and which from older human literature.

A short, well-defined, acidic peptide with one UV-active residue is handy for analytical chemists. DSIP works as a test analyte when tuning gradients, checking negative-mode mass spectrometry, or comparing column chemistries for polar peptides.

The published literature, meanwhile, falls into three study types. The table lists what kind of work exists in each, not what it found.

In vitro	Animal	Human
Degradation and aggregation studies in plasma and serum (Peptides, 1987)	Original isolation from rabbit tissue (1977)	Small clinical reports from the 1980s, such as a pilot study in European Neurology (1984)
Analytical method work: HPLC, LC-MS, peptide mapping	Immunohistochemical mapping of DSIP-like immunoreactivity in tissues	Measurement of DSIP-like immunoreactivity in plasma samples
Antibody and immunoassay development	Comparisons of native vs synthetic material (1977)	Few studies, mostly before 2000

One caution applies to immunoassays. In 1993, a team characterized a 77-residue protein from porcine brain that an anti-DSIP antiserum also recognized (European Journal of Biochemistry, 1993). “DSIP-like immunoreactivity” therefore doesn’t always mean DSIP itself, and mass spectrometry is the tiebreaker.

What’s still missing is a target. As Kovalzon and Strekalova’s review describes, no specific DSIP receptor has been isolated. Receptor-binding assays, which anchor work on most peptides, have no confirmed partner to run against here. That’s one reason so much DSIP literature is analytical or descriptive: identity, stability, distribution of immunoreactivity. For a lab, it also means every experiment leans hard on knowing exactly what’s in the vial.

How Do You Read a DSIP COA?

Quick answer: A DSIP COA should show the lot number, HPLC purity with a chromatogram, and LC-MS identity matching about 848.8 Da. It should also give appearance, test date and the testing lab. Purity is reported per batch, so check the result for your lot rather than a headline figure. Endotoxin or heavy-metal panels appear only if they were run.

These are the ions to look for, calculated from the monoisotopic mass of 848.3301 Da:

Ion	Expected m/z	When you’ll see it
[M+H]+	849.34	Positive-mode ESI, the usual default
[M+2H]2+	425.17	Positive mode, smaller share for an acidic peptide
[M−H]−	847.32	Negative mode, which suits DSIP’s acidic residues
[M+O+H]+	865.33	Trp oxidation product; should be absent or a trace

For a field-by-field walkthrough of any certificate, see how to read a peptide COA.

HPLC purity vs MS identity

Each test covers a different blind spot. HPLC pulls the sample apart on a column and measures what share of the UV signal lands in the main peak. LC-MS weighs that peak to show it really is DSIP.

DSIP adds a twist. Its tryptophan absorbs at 280 nm, while every peptide bond absorbs at 214 nm. A COA that shows both wavelengths can flag impurities that lack the Trp residue, such as truncated sequences missing position 1. The trade-offs between the two methods are covered in HPLC vs mass spectrometry.

Mass ruler of calculated DSIP-related ions: des-Trp 663.26, sodium adduct 871.32, double oxidation 881.33 and N-acetyl 891.35, beside the protonated DSIP ion

Red flags on a peptide COA

Run down this list before filing any certificate:

• No lot match. The batch number differs from the vial label, or there isn’t one.
• No chromatogram. A bare percentage leaves you nothing to check.
• A recycled date. The same test date appears across lots made months apart.
• No lab name. An anonymous report can’t be traced or confirmed.
• The wrong mass. An ion near 865 or 929 suggests an oxidized or phosphorylated form, not DSIP.

If something looks off, here’s how to spot a fake COA.

How Should DSIP Be Stored?

Quick answer: Store lyophilized DSIP at −20 °C or below, dry, sealed and protected from light. Let the vial reach room temperature before opening to limit moisture uptake. Record the lot number and receipt date. Storage affects how well a sample’s analytical results stay valid over time.

Light protection has a chemical reason here. Tryptophan’s indole ring is the residue most prone to oxidation, and each added oxygen shows up as a +16 Da peak on a later mass spectrum. Keeping the vial dark and dry slows that drift, so a re-test months later still matches the original COA.

Moisture is the other enemy. A lyophilized cake pulls water from humid air, and absorbed water both lowers net peptide content and speeds hydrolysis, which is why a cold vial should warm up before the cap comes off.

A simple log helps: lot number, date received, freezer location and any re-test dates. More detail on sealed-vial handling is in our peptide storage guide.

What Is DSIP’s Regulatory Status in the US?

Quick answer: As of October 2026, DSIP (Emideltide) is not an FDA-approved drug, and FDA says neither the free base nor the acetate is part of any FDA-approved product. In the US it’s sold as a research-use-only chemical for laboratory work, not for human or veterinary use. Check FDA’s current compounding lists before relying on any summary.

Here’s where things stand, each line dated and sourced:

• Approval status. As of October 2026, no Emideltide product appears in FDA’s Drugs@FDA database (source: openFDA, checked October 18, 2026).
• Compounding review. FDA’s briefing for the July 23 and 24, 2026 Pharmacy Compounding Advisory Committee proposed that both the free base and the acetate salt of Emideltide be left off the 503A Bulks List, and noted that neither form has a USP or NF monograph (source: FDA briefing document, July 2026).
• The vote. On July 24, 2026, the committee voted 6 in favor, 7 against, with 1 abstention, on including Emideltide (source: FDA meeting page, July 2026).
• What that vote means. Committee votes are advice to FDA. Any change to the list requires notice-and-comment rulemaking (source: Federal Register notice, April 16, 2026).

What “research use only” means. Under 21 CFR 201.128, a product’s intended use is judged by objective evidence, including labeling, advertising and the circumstances of sale. An RUO label only holds up when everything around the product, including the way it’s described and sold, keeps it in the lab. Treat this as background reading; it isn’t legal advice.

Sources box (all accessed October 18, 2026): FDA PCAC July 23 and 24, 2026 meeting page and briefing document; Federal Register, April 16, 2026; openFDA Drugs@FDA; 21 CFR 201.128 (eCFR).

Sourcing DSIP in the US: What to Check in a Supplier

Every DSIP peptide supplier in the USA says “tested.” The way to tell them apart is to request proof you can confirm on your own. Here’s what to look for, with how Life Link handles each one.

One COA per lot. The certificate should carry the same lot as the vial in your hand, not a sample batch from last year. Life Link publishes a batch-specific report for each product, and identity (LC-MS) and purity (RP-HPLC) are run on every batch. Purity by HPLC, see the batch result.

Who did the testing. An outside lab has no stake in the result. Our reports come from Janoshik Analytical or US-based laboratories, and the reasons are set out in third-party vs in-house testing. Secondary panels (heavy metals, endotoxin and sterility) rotate through the catalog on a schedule, as described in our testing process.

US dispatch and transit. Long, warm journeys are hard on any peptide. Orders placed before 2 PM PST ship the same day by UPS 2-Day Air from California. Details are in our US shipping policy.

Packaging. Lyophilized peptides travel best sealed, dry and out of direct light. Life Link ships in plain, secure outer packaging with nothing on the outside to show the contents. When the parcel arrives, check the seal, match the lot to its COA and move the vial into cold storage the same day.

Clear RUO terms. A serious supplier states research-use-only terms plainly and sells to qualified researchers aged 21 and over.

For a longer checklist, read choosing a US peptide supplier. When you’re ready to order, the DSIP 5 mg research peptide page links its current batch report.

DSIP vs Selank and Semax: Structural Differences

These three short peptides often share a catalog page, but chemically they have little in common. DSIP is a native sequence. Selank and Semax are synthetic designs that each graft the same Pro-Gly-Pro tail onto a short fragment of a larger natural peptide.

	DSIP	Selank	Semax
Residues	9	7	7
Sequence	WAGGDASGE	TKPRPGP	MEHFPGP
Origin	Native sequence isolated from animal tissue	Synthetic analog: tuftsin (TKPR) + PGP	Synthetic analog: ACTH(4-7) fragment + PGP
Average MW	848.8 g/mol	751.9 g/mol	813.9 g/mol
Net character	Acidic	Basic (Lys, Arg)	Mixed
Supply form	Lyophilized	Lyophilized	Lyophilized

Comparing residue composition: DSIP 33% glycine, Selank 43% proline, Semax 29% proline

The proline-rich tails make Selank and Semax look alike on paper, while DSIP’s glycine-rich, acidic backbone separates it from both on an HPLC column. Product pages: Selank 10 mg and Semax 10 mg.

FAQs

Is DSIP the same as Emideltide?

Yes. Emideltide is the INN (international nonproprietary name) given to DSIP, the nonapeptide WAGGDASGE. Regulators, including FDA in its 2026 compounding documents, use Emideltide, while catalogs and older papers tend to say DSIP. Both names point to CAS 62568-57-4 and PubChem CID 68816, so searching both gives fuller results.

What is the molecular weight of DSIP?

Built from the formula C35H48N10O15, DSIP averages 848.8 g/mol. Its monoisotopic mass is 848.3301 Da, so a mass spectrometer in positive mode should show an [M+H]+ ion near 849.34. A salt form or a phosphorylated variant will read differently, so check which form a COA describes.

What is the CAS number for DSIP?

The CAS Registry Number for DSIP (Emideltide) is 62568-57-4. Useful cross-references are PubChem CID 68816 and FDA UNII YN28Z5YZ73. N-acetyl Emideltide has its own separate UNII, CL985USD2K, so confirm that any identifier on a supplier’s document matches the unmodified peptide you ordered.

Does DSIP come with a batch COA?

It should, and every lot should have its own. At Life Link, each DSIP batch is tested for identity by LC-MS and for purity by RP-HPLC, and the report lists the batch number, test date and testing lab. Check the vial’s lot against the certificate before the sample goes into inventory.

Is DSIP FDA-approved?

No. As of October 2026, Emideltide isn’t an FDA-approved drug, and FDA’s July 2026 briefing says neither the free base nor the acetate form is part of any approved product. An FDA advisory committee voted 6 to 7, with one abstention, against listing it for 503A compounding.

Is DSIP sold for human use?

No. Life Link sells DSIP strictly as a research-use-only chemical for laboratory and in vitro work by qualified researchers aged 21 and over. It isn’t for human or veterinary use, and this page doesn’t describe administration. The product’s label and terms of sale both reflect that limit.

Research use notice. For Research Use Only. Not for use in diagnostic or therapeutic procedures. Life Link Research supplies DSIP as a lab reagent to qualified professionals. It has not been evaluated or approved by FDA, and none of this page is medical advice. Our terms and conditions set out how we supply it. Read our full Research Use Disclaimer. Last updated October 18, 2026.

References

Sources checked on October 18, 2026.

• Schoenenberger GA, Maier PF, Tobler HJ, Monnier M. Pflügers Archiv. 1977;369(2):99-109. Isolation from rabbit tissue (animal). doi:10.1007/BF00591565
• Schoenenberger GA, Monnier M. Proceedings of the National Academy of Sciences. 1977;74(3):1282-1286. Sequence characterization (animal tissue). doi:10.1073/pnas.74.3.1282
• Monnier M, Dudler L, Gächter R, et al. Experientia. 1977. Native vs synthetic peptide comparison. doi:10.1007/BF01922266
• Kovalzon VM, Strekalova TV. Journal of Neurochemistry. 2006;97(2):303-309. Review. doi:10.1111/j.1471-4159.2006.03693.x
• Graf MV, Saegesser B, Schoenenberger GA. Peptides. 1987;8(4):599-603. In vitro (plasma and serum). PubMed 3628078
• Sillard R, Schulz-Knappe P, Vogel P, et al. European Journal of Biochemistry. 1993;216(2):429-436. Protein isolation from porcine brain tissue. doi:10.1111/j.1432-1033.1993.tb18160.x
• Larbig W, Gerber WD, Kluck M, et al. European Neurology. 1984;23(5):372-385. Small human pilot study. doi:10.1159/000115716
• Roy K, Chauhan G, Kumari P, et al. Life Sciences. 2018. Animal study. doi:10.1016/j.lfs.2018.08.026
• PubChem, Emideltide, CID 68816
• FDA Global Substance Registration System, Emideltide, UNII YN28Z5YZ73
• FDA, Pharmacy Compounding Advisory Committee, July 23 and 24, 2026: meeting page
• FDA, PCAC briefing document, July 2026: emideltide briefing
• Federal Register, April 16, 2026, PCAC meeting notice and public docket: 2026-07361
• openFDA, Drugs@FDA database, searched October 18, 2026: open.fda.gov
• Code of Federal Regulations, 21 CFR 201.128

Ipamorelin is a synthetic five-residue peptide that acts as an agonist at the ghrelin receptor, GHSR-1a. It started life as a subtraction. Chemists at Novo Nordisk took an older seven-residue research peptide, cut two amino acids out of its middle, swapped in non-natural building blocks, and the shorter molecule still engaged the receptor.

Before a lab orders an Ipamorelin 10 mg research peptide, it helps to know three things, and the sections below follow that order: the structure and its identifiers, the receptor and the assays built around it, and what a batch’s certificate of analysis (COA) ought to carry.

For Research Use Only. Not for use in diagnostic or therapeutic procedures.

What Is Ipamorelin?

Quick answer: Ipamorelin is a synthetic pentapeptide (Aib-His-D-2Nal-D-Phe-Lys-NH2) first described by Novo Nordisk researchers in 1998 under the code NNC 26-0161. It’s classed as an agonist at the growth hormone secretagogue receptor (GHSR-1a), the receptor bound by the endogenous ligand ghrelin. Research-grade Ipamorelin is a reference material for receptor-binding and signaling assays.

The founding paper is “Ipamorelin, the first selective growth hormone secretagogue” (Raun et al., European Journal of Endocrinology, 1998), an in vitro and animal characterization.

Where the molecule came from. The Novo Nordisk team reported finding Ipamorelin “within a series of compounds lacking the central dipeptide Ala-Trp” of the earlier synthetic peptide GHRP-1. Line the two up and the edit is plain to see:

• GHRP-1: Ala-His-D-2Nal-Ala-Trp-D-Phe-Lys-NH2 (seven residues)
• Ipamorelin: Aib-His-D-2Nal-D-Phe-Lys-NH2 (five residues)

Two residues came out, and the N-terminal alanine became Aib, a small change with big chemical consequences (more on that below).

Why labs reach for it. At five residues and under 712 Da, Ipamorelin handles almost like a small molecule. Its structure is fully defined, it carries no lipid chain or disulfide bond, and mass spec confirms it quickly. That makes it a clean synthetic agonist to run beside ghrelin itself, a 28-residue peptide whose octanoyl ester is harder to make and keep intact.

What Is the Chemical Structure of Ipamorelin?

Quick answer: Ipamorelin has five residues: α-aminoisobutyric acid (Aib), L-histidine, D-2-naphthylalanine, D-phenylalanine and L-lysine, with a C-terminal amide. Its formula is C38H49N9O5 and its average molecular weight is about 711.9 g/mol (CAS 170851-70-4). Two D-amino acids plus the non-natural Aib and 2-Nal residues set it apart from natural peptides.

Every value below was checked against the registry named in the Source column on October 18, 2026.

Field	Value	Source
Name	Ipamorelin (development code NNC 26-0161)	PubChem
Sequence (three-letter)	Aib-His-D-2Nal-D-Phe-Lys-NH2	Raun et al., 1998
Sequence (one-letter style)	Aib-H-(D-2Nal)-(D-F)-K-NH2 (Aib and 2-Nal have no standard one-letter code)	Derived from the above
Molecular formula	C38H49N9O5	PubChem
Average molecular weight	711.9 g/mol (free base)	PubChem
Monoisotopic mass	711.3857 Da	PubChem
CAS number	170851-70-4	PubChem synonyms
PubChem CID	9831659	PubChem
ChEMBL ID	CHEMBL58547	ChEMBL
FDA UNII	Y9M3S784Z6	FDA GSRS
Common salt form	Acetate	FDA PCAC docket, October 2024

One thing to know about the UNII lookup: GSRS also holds a separate record for N-acetyl Ipamorelin (UNII 8NU4QJ4VFG). It’s a different substance, so make sure a search lands on the right one.

How D-amino acids and Aib shape peptide design

Proteases evolved to cut bonds between L-amino acids. Flip a residue to its D-form and its side chain points the wrong way for the enzyme’s binding pocket, so the neighboring bond becomes a poor substrate. That’s why D-residues are a standard design move when a peptide needs to survive serum-stability or tissue-homogenate assays.

Aib does a different job. It carries two methyl groups on its α-carbon, which pins the backbone into a narrow range of angles and favors turn or helix shapes. Placed at the N-terminus, it also blocks aminopeptidases that nibble peptides from that end. The bulky, bicyclic 2-naphthylalanine adds a large aromatic surface for receptor contact.

Free base vs acetate salt: why molecular weights differ

PubChem lists the free base. Most research peptides, though, leave HPLC purification as acetate salts. Ipamorelin has three basic sites (the N-terminal amine, the histidine ring and the lysine side chain), and every acetate it binds puts roughly 60.05 g/mol on the scale. A monoacetate weighs roughly 771.9 g/mol, a diacetate roughly 831.9. It’s the same peptide on a different weighing basis, which is exactly what the COA section below untangles. For a refresher on residues and bonds, see our peptide structure basics.

The share of each milligram that is ipamorelin: 100% free base, 92.2% with one acetate, 85.6% with two, 79.8% with three

What Receptor Does Ipamorelin Bind? GHSR-1a Explained

Quick answer: Ipamorelin is an agonist at GHSR-1a, the growth hormone secretagogue receptor type 1a. GHSR-1a is a class A G protein-coupled receptor whose endogenous ligand is acyl-ghrelin. It signals mainly through Gq/11, activating phospholipase C and mobilizing intracellular calcium. That’s why calcium-flux and IP-1 accumulation assays are standard read-outs.

GHSR-1a at a glance

Property	Detail
Gene	GHSR
Receptor class	Class A (rhodopsin-like) GPCR, seven transmembrane helices
Endogenous ligand	Acyl-ghrelin: 28 residues, with an n-octanoyl group on serine 3 that the discovery paper found essential for activity
Main coupling	Gq/11 → phospholipase C → IP3 → calcium release
Other pathway	β-arrestin recruitment
Basal activity	High constitutive (ligand-independent) signaling
Splice variant	GHSR-1b, a truncated form that doesn’t signal
Key papers	Receptor cloned by Howard et al., Science, 1996; ghrelin identified by Kojima et al., Nature, 1999

That basal activity is unusual. Working in transfected COS-7 and HEK293 cells (in vitro), a University of Copenhagen team led by Birgitte Holst concluded that “the ghrelin receptor is highly constitutively active” (Molecular Endocrinology, 2003). Kojima’s team, for their part, coined “ghrelin” from ghre, the Proto-Indo-European root for “grow.”

What “selective GHSR agonist” means

The 1998 paper called Ipamorelin the first selective growth hormone secretagogue, a label drawn from in vitro cell work and animal pharmacology. In receptor terms, “selective” means activity concentrated at one target at the concentrations tested.

What the label doesn’t give you is a full off-target panel. Labs that need receptor-level selectivity usually run their own counter-screens, testing the compound across a panel of related GPCRs at matched concentrations and comparing the curves. The motilin receptor, GHSR’s closest relative, is a common choice, and Holst’s group used it as the negative control in that 2003 study.

Common GHSR-1a assays that use Ipamorelin

Assay	Read-out	Notes
Radioligand competition binding	Displacement of labelled ghrelin (often ¹²⁵I-ghrelin); gives Ki	Measures affinity only, not activation
Calcium mobilization (Fluo-4 or FLIPR)	Fluorescence spike within seconds	Fast, plate-based; suits concentration-response curves
IP-1 accumulation (HTRF)	IP-1 builds up when LiCl blocks its breakdown	Stable end-point; also shows the high basal signal
β-arrestin recruitment (BRET or enzyme complementation)	Luminescence or energy-transfer signal	Used to compare pathway bias

Ipamorelin usually runs as a reference agonist beside ghrelin, and plotting both as concentration-response curves gives a direct read on relative potency (EC50) and maximal effect in the same plate. Because the receptor is so active at baseline, many teams add an inverse agonist control. Holst’s group identified [D-Arg1,D-Phe5,D-Trp7,9,Leu11]-substance P as a potent one (EC50 5.2 nM, in vitro). Our GHSR and GHRH-receptor research peptides collect the related reference materials.

What Should an Ipamorelin COA Show?

Quick answer: A batch COA for Ipamorelin should carry the lot number printed on your vial, the HPLC purity with its chromatogram, and a mass-spectrometry identity result close to the expected [M+H]+ of about 712.4. Useful extras are net peptide content, counter-ion (usually acetate), water content, the name of the testing lab and the report date.

Ipamorelin COA field checklist

The masses below come from PubChem’s monoisotopic value (711.3857 Da) plus one or two protons.

Field	What it confirms	What to look for
Lot number	The report belongs to your vial	Exact match to the vial label
HPLC purity + chromatogram	Proportion of target peptide in the material	A percentage backed by a visible trace with a dominant main peak
MS identity	The molecule is Ipamorelin	[M+H]+ ≈ 712.39; [M+2H]2+ ≈ 356.70
Net peptide content	Peptide mass vs counter-ion and water	A stated percentage, reported separately from HPLC purity
Counter-ion	Salt form	Acetate in most cases; trifluoroacetate (TFA) should be named if present
Water (Karl Fischer)	Moisture in the solid	A stated percentage
Appearance	Physical form	White to off-white solid
Lab and date	Who tested it and when	The lab’s name plus a report date close to manufacture
Endotoxin (optional)	Bacterial endotoxin level	Stated as a specification, e.g. EU/mg

Each block is unpacked in our guide on how to read a peptide COA.

HPLC purity vs MS identity

Think of HPLC as a headcount and MS as an ID check. The first says what proportion of the material is one compound; the second says which compound that is. A tall, clean HPLC peak might belong to the wrong peptide, and a correct mass can turn up inside a messy sample. Peptide bonds absorb strongly in the low UV range, so purity runs typically use reversed-phase HPLC read at 210 to 220 nanometers. A trustworthy COA reports both results for the same lot. Our guide to HPLC vs mass spectrometry covers how the two methods work.

Ipamorelin’s five residues with calculated b-ions (b2 223.12, b3 420.20, b4 567.27) above and y-ions (y4 627.34 to y1 146.13) below

Red flags on an Ipamorelin COA

Most problems show up within a minute of reading, once you know where to look:

• A missing lot number, or one that differs from the vial label
• A purity figure with no chromatogram attached
• A mass that fits neither the free base nor a known salt (an [M+H]+ near 754.4 points to N-acetyl Ipamorelin, a different substance)
• “99%+” printed with no trace behind it
• A report dated years before the batch
• The same COA reused across several lots

To test a document yourself, follow our steps to check whether a COA is genuine. For what a percentage point really represents, see 98% vs 99% purity.

Where to find the Life Link batch result

Purity by HPLC, see the batch result. Every Ipamorelin lot is tested for identity (LC-MS) and purity (RP-HPLC) by Janoshik Analytical or a US-based laboratory, and the report is posted with its batch number and test date. Heavy metals, endotoxin and sterility run on a rotating cycle across the catalog. Read why we use outside labs in third-party vs in-house testing.

How Is Research-Grade Ipamorelin Supplied and Stored?

Quick answer: Research-grade Ipamorelin is generally supplied as a lyophilized (freeze-dried) white solid, most often the acetate salt, in a sealed vial. Unopened vials are typically kept at −20 °C, in the dark and dry. For laboratory work it’s soluble in water or DMSO for assay preparation. Follow your lab’s SOPs for handling.

A few checks on arrival save trouble later:

• Match the vial’s lot number to the COA before logging it into inventory.
• Confirm the seal and cap are intact.
• Record the receipt date and storage location against the lot number.

Why freeze-dried? Removing water slows the hydrolysis and oxidation reactions that degrade peptides in storage, so a dry solid keeps far longer than anything in liquid form. The acetate salt is preferred over trifluoroacetate (TFA) in many labs because residual TFA can interfere with some cell-based assays.

Our quality testing process explains what happens to each batch before it ships.

Is Ipamorelin FDA-Approved? (Regulatory Status)

Quick answer: No. Checked on October 18, 2026, Ipamorelin is still not an FDA-approved drug in the United States, and the FDA’s drug approvals database returns no Ipamorelin records (source: openFDA Drugs@FDA, checked October 18, 2026). FDA has reviewed it as a bulk drug substance for compounding. Life Link supplies it strictly as a research chemical. For Research Use Only. Not for use in diagnostic or therapeutic procedures.

FDA compounding (503A) status

On October 29, 2024, FDA’s Pharmacy Compounding Advisory Committee (PCAC) considered Ipamorelin acetate and Ipamorelin free base for the 503A Bulks List (source: FDA PCAC meeting page, October 29, 2024). The meeting transcript notes the nominations were withdrawn on September 19, 2024, and FDA presented them anyway (source: FDA PCAC transcript, October 29, 2024). The committee voted against inclusion.

The committee’s July 2026 session dealt with seven other peptides, and Ipamorelin wasn’t on that agenda. Pharmacies operating under Section 503A can compound only with bulk ingredients that clear this review, and the committee’s votes are advice to FDA rather than decisions; any listing still goes through rulemaking. For background on how the list works, see our FDA 503A bulks list explained.

Anti-doping lists

The WADA 2026 Prohibited List, in force from January 1, 2026, names Ipamorelin under S2 among its growth hormone secretagogue examples, alongside anamorelin, ibutamoren and macimorelin (source: WADA Prohibited List, 2026 edition).

How Is Ipamorelin Different From CJC-1295?

Quick answer: Ipamorelin is a GHSR-1a (ghrelin receptor) agonist. CJC-1295 is a GHRH analogue that acts at the GHRH receptor, a class B GPCR coupled to Gs and cAMP. Sermorelin, the unmodified GHRH(1-29) sequence, works through that same receptor; our ipamorelin vs sermorelin comparison covers how the two differ. The two target different receptors and are measured with different signaling read-outs. For the full side-by-side comparison, see our CJC-1295 vs Ipamorelin guide.

	Ipamorelin	CJC-1295
Receptor	GHSR-1a (class A)	GHRH receptor (class B)
Main coupling	Gq/11	Gs
Typical read-out	Calcium flux, IP-1	cAMP accumulation

On the bench, the difference shows up in the read-out: a Gs-coupled GHRH receptor response shows up in a cAMP assay, while a GHSR-1a response shows up as calcium or IP-1. Some catalogs, ours included, also list a CJC-1295 no DAC / Ipamorelin 5 mg + 5 mg mixture as a single composition.

Ipamorelin FAQs

What is the amino acid sequence of Ipamorelin?

Ipamorelin’s sequence is Aib-His-D-2Nal-D-Phe-Lys-NH2. Reading from the N-terminus, that’s α-aminoisobutyric acid, L-histidine, D-2-naphthylalanine, D-phenylalanine and L-lysine, finished with a C-terminal amide instead of a free acid. Two residues (Aib and 2-Nal) are non-natural, and two (2-Nal and Phe) are in the D-configuration.

What is the molecular weight of Ipamorelin?

Ipamorelin free base weighs 711.9 g/mol on average, with a monoisotopic mass of 711.3857 Da (PubChem CID 9831659). Mass spectrometry usually reports the protonated ion, so expect an [M+H]+ near 712.39 or a doubly charged ion near 356.70. Salt forms weigh more on paper.

What is Ipamorelin’s CAS number?

Ipamorelin’s CAS Registry Number is 170851-70-4, which refers to the free base. Other identifiers that point to the same molecule are PubChem CID 9831659, ChEMBL ID CHEMBL58547 and FDA UNII Y9M3S784Z6. Acetate and other salts can carry their own registry entries, so match the identifier to the form on the label.

Is Ipamorelin a ghrelin mimetic?

In receptor terms, yes. Ipamorelin activates GHSR-1a, the same receptor that acyl-ghrelin binds, so it’s grouped with ghrelin receptor agonists. The two look nothing alike, though. Ghrelin runs to 28 residues and carries an octanoyl group on serine 3, while Ipamorelin is a five-residue synthetic peptide with no lipid chain.

Where does the name “growth hormone secretagogue receptor” come from?

The receptor was named after the compounds used to find it. In 1996, Howard and colleagues at Merck cloned it as the target of synthetic “growth hormone secretagogues,” three years before anyone knew its natural ligand. When Kojima’s team identified ghrelin in 1999, the original name stayed, which is why ghrelin’s receptor still carries a drug-class label.

Why does the molecular weight on a COA differ from PubChem?

PubChem lists the free base at 711.9 g/mol, while research material is usually an acetate salt. With roughly 60 g/mol per acetate, the figure on a COA or label can run higher. Net peptide content then gives the peptide share of the solid, with counter-ion and water making up the rest.

Ipamorelin at a Glance

Property	Value
Sequence	Aib-His-D-2Nal-D-Phe-Lys-NH2
Formula	C38H49N9O5
Molecular weight	711.9 g/mol (free base)
CAS	170851-70-4
Receptor	GHSR-1a (ghrelin receptor), class A GPCR
Assay read-outs	Calcium flux, IP-1, β-arrestin recruitment, radioligand binding
COA fields	Lot, HPLC purity + trace, MS identity, net peptide content, counter-ion, water, lab, date

Research use only. Life Link Research supplies Ipamorelin as a laboratory reagent for in vitro research by qualified professionals aged 21 and over. Human and veterinary use are excluded. For Research Use Only. Not for use in diagnostic or therapeutic procedures. Full supply terms are in our Terms and Conditions. Read our full Research Use Disclaimer.

References

All accessed October 18, 2026.

• Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561. In vitro and animal study. doi:10.1530/eje.0.1390552
• Howard AD, et al. Science. 1996;273(5277):974-977. Receptor cloning, in vitro. doi:10.1126/science.273.5277.974
• Kojima M, et al. Nature. 1999;402(6762):656-660. Ligand identification, in vitro and animal. doi:10.1038/45230
• Holst B, et al. High constitutive signaling of the ghrelin receptor. Mol Endocrinol. 2003;17(11):2201-2210. In vitro. doi:10.1210/me.2003-0069
• PubChem CID 9831659, ChEMBL CHEMBL58547, FDA GSRS UNII Y9M3S784Z6
• FDA Pharmacy Compounding Advisory Committee, meeting of October 29, 2024
• WADA Prohibited List, 2026 edition

Gonadorelin is the synthetic decapeptide carrying the same sequence as mammalian GnRH-I, the peptide that gave its receptor a name. Ten residues, both ends chemically blocked, and a single G protein-coupled receptor to bind: on paper it looks like one of the simplest peptides a laboratory can work with.

The pharmacology underneath is less simple. This overview covers the sequence and structure, the salt forms that change what a vial actually contains, the GnRH receptor and its unusual architecture, the signalling readouts used to measure it, how to verify a batch, and where the compound stands with the FDA. New to peptide reagents? Start with our introduction to research peptides.

Fact	Value
Name	Gonadorelin
Synonyms	GnRH, LHRH (GnRH-I)
Sequence	pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH₂
Length	10 residues
Molecular weight	1,182.3 g/mol, free base (PubChem CID 638793)
CAS, free base	33515-09-2
CAS, acetate	34973-08-5 (diacetate tetrahydrate: 52699-48-6)
Common salt	Acetate
Target	GnRH receptor (GnRHR, gene GNRHR), class A GPCR
Primary coupling	Gq/11
Form	Lyophilized powder
Status	Research use only

What Is Gonadorelin?

Gonadorelin is the synthetic form of gonadotropin-releasing hormone (GnRH-I), a 10-amino-acid peptide with a blocked pyroglutamate N-terminus and an amidated C-terminus. It binds the GnRH receptor (GnRHR), a class A G protein-coupled receptor, and serves in research as the reference agonist for that receptor.

The name belongs to the manufactured material. “Gonadorelin” is the international nonproprietary name (INN) assigned to the synthetic peptide, which is why catalogues, pharmacopoeias and regulatory records use it while the physiology literature says GnRH.

Decapeptides of this family turn up across vertebrates with small sequence variations, and the mammalian form is the one gonadorelin reproduces. For a laboratory, the appeal is that a short synthetic sequence gives you the same ligand the receptor evolved around, with none of the batch variability of extracted material.

Gonadorelin vs GnRH: What’s the Difference?

Chemically there is none: gonadorelin has the same 10-residue sequence as native mammalian GnRH-I. The difference is origin and form. “GnRH” names the endogenous peptide, while “gonadorelin” names the synthetic material, usually supplied as an acetate salt, so its batch COA reports salt and net peptide content.

So the two words point at the same molecule from different angles. One is a biological entity, the other is a manufactured reagent with a lot number.

LHRH, short for luteinising hormone-releasing hormone, is an older synonym for the same peptide and still appears in literature from the 1970s and 1980s, along with catalogue listings that have never been renamed.

A second human decapeptide, GnRH-II, exists and differs at three positions. Its mature sequence reads pGlu-His-Trp-Ser-His-Gly-Trp-Tyr-Pro-Gly-NH₂ (UniProt O43555), so positions 5, 7 and 8 carry histidine, tryptophan and tyrosine where GnRH-I carries tyrosine, leucine and arginine. A type II receptor exists in many vertebrates, though in humans the gene carries a frameshift and is not expressed as a full receptor.

What Is the Structure of Gonadorelin?

Gonadorelin is a linear decapeptide: pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH₂. Both ends are blocked, by a pyroglutamate ring at the N-terminus and an amide at the C-terminus. Glycine at position 6 allows a β-turn that folds the peptide into its receptor-binding shape, and positions 6 and 10 are where most synthetic analogs are modified.

The two blocked termini are the first thing to notice. Neither end carries the free amine or free acid a standard synthetic peptide would, which changes both its chemistry and the mass you should expect on a certificate.

Residue by residue

Gonadorelin decapeptide showing all ten residues from pGlu to Gly-amide, with both blocked ends and the glycine 6 turn highlighted

Position	Residue	Structural note
1	pGlu	Cyclised glutamine, blocks the N-terminus
2	His	Part of the agonist-activity region
3	Trp	Part of the agonist-activity region
4	Ser	Flexible linker toward the turn
5	Tyr	Proposed receptor contact
6	Gly	Permits the β-turn
7	Leu	Hydrophobic, follows the turn
8	Arg	Required for high-affinity binding
9	Pro	Rigid, sets the C-terminal geometry
10	Gly-NH₂	Amidated, blocks the C-terminus

The Gly6 β-turn

Flanagan and Manilall (2017) describe the predominant conformer as “a β-turn that brings the amino- and carboxy-termini close together,” so the peptide folds back on itself. Their review assigns distinct jobs to the two ends: the N-terminal residues pGlu1, His2 and Trp3 drive agonist activity, while the C-terminal residues, “particularly Arg8, are necessary for high affinity binding.”

Why the native sequence is short-lived in assay matrices

Glycine at position 6 occupies the middle of the molecule with no side chain, and the Tyr5-Gly6 and Gly6-Leu7 bonds around it are the classic cleavage points for peptidases present in serum-containing media and tissue homogenates. Plan assay timing around that, and run a vehicle-matched control, since the peptide’s working life in a buffer differs from its life in a complex matrix.

How analogs change positions 6 and 10

Two chemical strategies dominate the analog literature, and both target the turn or the tail. Substituting a D-amino acid at position 6 stabilises the β-turn, a change that Flanagan and Manilall note increases receptor-binding affinity. Replacing the C-terminal Gly10-NH₂ with an ethylamide group is the other common modification. Both changes also remove a preferred cleavage site, which is why analog chemistry and stability chemistry tend to arrive together.

What Is the GnRH Receptor (GnRHR)?

The GnRH receptor (GnRHR, gene GNRHR) is a class A, seven-transmembrane G protein-coupled receptor. The mammalian type I receptor is unusual because it lacks the C-terminal tail most GPCRs carry, which is linked to its distinctive desensitisation behaviour in cell studies. It is studied in gonadotroph-derived cell lines such as αT3-1 and LβT2.

Receptor architecture

GnRHR belongs to class A, the rhodopsin-like family, and its fold is the standard “bundle of seven membrane-spanning α-helical segments.” Mutagenesis work has mapped several contacts between receptor and ligand: Asp7.32(302) is proposed to form a salt bridge with Arg8 of the peptide, and Tyr6.58(290) has been proposed as a contact for Tyr5. Other assignments remain open, and Flanagan and Manilall call it “uncertain whether Lys3.32(121) directly contacts GnRH or initiates receptor activation.”

The missing C-terminal tail

Here is the structural oddity. The mammalian type I receptor is “characterized by absence of a cytoplasmic carboxy-terminal tail,” the segment where most GPCRs are phosphorylated and where arrestin is recruited. Flanagan and Manilall report that the receptor “does not activate β-arrestin-dependent signaling,” leaving its output to run through G protein coupling. Type II receptors in other species do carry the tail, which makes the pair a natural comparison for studying what the tail contributes. Receptors in the same broad GPCR superfamily vary widely in this respect, and a useful contrast is B7-33 and the RXFP1 receptor, where a large extracellular domain does work that GnRHR handles within the helical bundle.

Cell models

Three systems carry most of the published work. The αT3-1 and LβT2 lines are gonadotroph-derived and express the receptor natively, with LβT2 the more mature of the two. HEK293 cells transfected with GnRHR give a cleaner background for binding and mutagenesis studies, which is where most receptor residue mapping has been done.

How Does Gonadorelin Signal Through the GnRH Receptor?

Gonadorelin binding activates GnRHR coupling to Gq/11, which stimulates phospholipase C-β. That produces IP3 and diacylglycerol, raising intracellular calcium and activating protein kinase C, followed by MAPK/ERK phosphorylation. In the laboratory these steps are measured as IP accumulation, calcium flux and pERK readouts.

The cascade runs in a fixed order, so each readout reports on a different depth of the pathway. Choosing between them is mostly a question of how far downstream the question lies and how fast the signal moves. Timing is the part that catches people out: a calcium response rises and falls within seconds to a couple of minutes, pERK peaks over several minutes, and IP accumulation is read as a total built up across half an hour or more. Sample at the wrong moment and a real response reads as no response at all.

Readout	What it measures	Typical format
Radioligand binding	Affinity of a ligand for the receptor	Competition binding on membranes or whole cells
IP-One / IP accumulation	PLC-β activity, one step after Gq/11	HTRF or similar plate assay, accumulation over 30 to 60 minutes
Ca²⁺ flux	Release of intracellular calcium stores	Dye-loaded cells read on a plate reader, seconds to minutes
pERK1/2	MAPK activation further downstream	Western blot or plate-based phospho-assay, minutes
β-arrestin recruitment	Arrestin engagement at the receptor	Reporter assay; expect little signal at the tail-less type I receptor

That last row is the practical consequence of the missing C-terminal tail. A β-arrestin assay that gives a flat response at GnRHR is reporting receptor biology, so confirm the assay with a positive-control receptor before concluding anything about the ligand.

Why Does Pulse Frequency Count in GnRH Receptor Research?

In cell and perifusion studies, continuous exposure to gonadorelin leads to receptor desensitisation and uncoupling, while intermittent pulses keep receptor signalling responsive. That is why pulse frequency is a key variable in GnRHR research design, and why perifusion systems that deliver timed pulses are used alongside static cell assays.

A static well of cells bathed in agonist for an hour and a perifusion chamber receiving five-minute pulses are two different experiments, and they can return different answers from the same compound.

Tsutsumi and colleagues (Journal of Biological Chemistry, 2010) examined signalling responses to pulsatile GnRH in LβT2 cells and showed that pathway activity tracks the pulse pattern as much as the total amount delivered. For anyone designing receptor work, three variables follow from that: pulse interval, pulse duration and washout between pulses, all of which belong in the methods section alongside concentration.

How Is Gonadorelin Used in Research?

Gonadorelin is used as the reference agonist in GnRH receptor studies: as the standard in binding and signalling assays, as the parent sequence for structure-activity work on analogs, and to study receptor desensitisation and internalisation in cell lines. It is supplied for research use only and not for any medical use.

Source	Year	Study type	Assay readout
Flanagan CA, Manilall A. Front Endocrinol 8:274	2017	Review of receptor structure and ligand binding	Binding determinants, receptor-residue contacts
Tsutsumi R et al. J Biol Chem 285:20262	2010	In vitro, LβT2 gonadotroph cell line	Signalling responses under pulsatile delivery
Manilall A et al. Mol Cell Endocrinol 481:53	2019	In vitro, receptor mutants in transfected cells	Ligand affinity and receptor activation

What Is Gonadorelin Acetate?

Gonadorelin acetate is the peptide supplied as an acetate salt, the most common form for research material. The salt and any bound water add mass, so net peptide content is lower than the vial weight. Other forms, such as the diacetate tetrahydrate, exist, and the batch COA should state which salt is present.

The arithmetic has consequences at the bench. Weigh out 2 mg of acetate salt, treat it as 2 mg of peptide, and every concentration in the experiment drifts high by whatever fraction the counterion and water contribute. Certificates that report a measured peptide content let you correct for it, which is covered in our guide to net peptide content on a COA.

The scale of the correction is easy to pin down. PubChem lists the monoacetate at 1,242.3 g/mol against 1,182.3 for the free base, so the counterion alone accounts for about 5 percent of the weight, and the tetrahydrate form carries bound water on top of that. A 2 mg vial weighed as peptide is therefore closer to 1.9 mg of peptide before any residual solvent or water is counted.

Comparison of gonadorelin free base at 1,182.3 g/mol against the monoacetate at 1,242.3 g/mol, and a 2.00 mg weighed vial against about 1.90 mg of peptide

How Do You Verify Gonadorelin Quality?

Confirm identity by mass spectrometry, where the observed mass should match roughly 1,182 Da for the free base, and purity by HPLC, then compare both with the batch result. Check that the COA names the salt form and reports net peptide content. Store the lyophilized powder cold, dry and away from light, as the label states.

Identity by mass spectrometry

The expected average mass is 1,182.3 Da for the free base, formula C55H75N17O13. Remember that the blocked termini are part of that figure: a report landing about 17 Da high suggests an unconverted glutamine at position 1, and about 1 Da high suggests a free acid where the C-terminal amide should be. See HPLC vs mass spectrometry for how the two methods divide the work.

Purity by HPLC

Read purity by HPLC, see the batch result, for the specific lot in hand. For what the figures mean in practice, see what 98% vs 99% purity means.

Third-party versus in-house testing

Who ran the assay carries as much weight as the number it produced. Our guide to third-party vs in-house testing sets out what each arrangement does and does not tell you.

Storage

Keep the sealed, lyophilized vial cold, dry and shielded from light, following the condition printed on the label. Gonadorelin is soluble in water for assay preparation. Our peptide storage guide covers handling of the dry form.

What Is Gonadorelin’s Regulatory Status in the US?

Gonadorelin has a history as an FDA-approved human drug product and as the active ingredient in approved animal drug products, which sets it apart from most research peptides. As of October 2026, research-grade gonadorelin is sold for laboratory use only. Check FDA sources for current product and compounding status.

Date	Event	Primary source
10 March 1978	Cystorelin (gonadorelin diacetate tetrahydrate) approved under NADA 098-379 as an animal drug product	Animal Drugs @ FDA
30 September 1982	Factrel (gonadorelin hydrochloride) approved under NDA 018123; marketing status now listed as discontinued	Drugs@FDA
10 October 1989	Lutrepulse Kit (gonadorelin acetate) approved under NDA 019687; marketing status now listed as discontinued	Drugs@FDA
October 2026	Both human products remain listed as discontinued in Drugs@FDA. Research-grade material is sold for laboratory use only	Drugs@FDA, read 12 October 2026

That approval history is the detail to carry away. Most research peptides have never held a US drug approval, so their status question is simple. Gonadorelin’s is a layered one: approved products that are no longer marketed, separate animal drug approvals that remain active, and research-grade material sold under a different framework entirely. Compounding categories are a further separate question, and our explainer on how FDA compounding lists work sets out how those lists operate.

Gonadorelin FAQs

Is gonadorelin the same as LHRH?

Yes, as a molecule. LHRH is an older name for the same decapeptide, used widely before GnRH became standard. Catalogues and papers from the 1970s and 1980s often use LHRH, so a literature search should cover both terms plus gonadorelin.

Is gonadorelin a peptide or a hormone?

Gonadorelin is a synthetic peptide with the same sequence as a peptide hormone. The word “hormone” describes the role the endogenous molecule plays, while “gonadorelin” describes manufactured material supplied as a laboratory reagent with a batch number and a certificate.

What kinds of compounds act at the GnRH receptor?

Two broad classes. Agonist analogs typically carry a D-amino acid at position 6 and often a modified C-terminus, which raises binding affinity and resists cleavage. Antagonist analogs carry several substitutions across the N-terminal residues that abolish the agonist activity while keeping receptor binding.

What is the molecular weight of gonadorelin?

1,182.3 g/mol for the free base, formula C55H75N17O13 (PubChem CID 638793). Material supplied as an acetate salt weighs more per vial, so check the salt form and the net peptide content on the certificate before calculating a concentration.

Does Life Link Research supply gonadorelin with a batch COA?

Yes. Our gonadorelin 2 mg research peptide ships with a batch-matched certificate from a third-party laboratory, covering identity by mass spectrometry and purity by HPLC for that lot.

References

Source	Date	Type
Flanagan CA, Manilall A. Gonadotropin-releasing hormone (GnRH) receptor structure and GnRH binding. Front Endocrinol 8:274. https://pmc.ncbi.nlm.nih.gov/articles/PMC5662886/	2017	Review
Tsutsumi R et al. Signaling responses to pulsatile gonadotropin-releasing hormone in LβT2 gonadotrope cells. J Biol Chem 285:20262. https://pmc.ncbi.nlm.nih.gov/articles/PMC2888439/	2010	Primary research
Manilall A et al. Glu2.53(90) of the GnRH receptor is part of the conserved G protein-coupled receptor structure. Mol Cell Endocrinol 481:53. https://pubmed.ncbi.nlm.nih.gov/30476558/	2019	Primary research
PubChem, gonadorelin, CID 638793. https://pubchem.ncbi.nlm.nih.gov/compound/638793	Accessed 12 Oct 2026	Chemical database
UniProt O43555, progonadoliberin-2. https://www.uniprot.org/uniprotkb/O43555/entry	Accessed 12 Oct 2026	Sequence database
Drugs@FDA, NDA 018123 and NDA 019687. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=018123	Accessed 12 Oct 2026	Regulatory record
Animal Drugs @ FDA, NADA 098-379. https://animaldrugsatfda.fda.gov/adafda/views/	Accessed 12 Oct 2026	Regulatory record

For Research Use Only. Not for use in diagnostic or therapeutic procedures. See our terms and research-use policy. Read our full Research Use Disclaimer.

This overview covers its structure and sequence, how it came out of relaxin-2, what cell assays have measured at RXFP1, and how to verify a vial before it reaches the bench. If peptide reagents are new to you, start with our introduction to research peptides.

Fact	Value
Name	B7-33
Class	Single-chain relaxin-2 B-chain analog
Origin	Hossain et al., Chemical Science, 2016
Length	27 residues
Sequence	VIKLSGRELVRAQIAISGMSTWSKRSL (C-terminal amide)
Molecular weight	2,986.6 Da (average), formula C131H229N41O36S
CAS number	1818415-56-3 (PubChem CID 162662592)
Target	RXFP1, also called LGR7
Signalling profile in cell assays	pERK1/2-biased, weak cAMP
Form	Lyophilized powder
Status	Research use only

In this guide

• What B7-33 is
• What relaxin-2 is
• How B7-33 was designed
• How B7-33 interacts with RXFP1
• What B7-33 is used for in research
• B7-33 vs relaxin-2 and other analogs
• Open questions
• Verification and storage
• FDA status
• FAQs
• References

What Is B7-33?

Quick answer: B7-33 is a synthetic, single-chain peptide derived from the B chain of human relaxin-2. Hossain and colleagues designed it (Chemical Science, 2016) as a simplified relaxin-2 analog that binds the RXFP1 receptor and, in cell assays, preferentially activates pERK1/2 signalling over cAMP. It is supplied for laboratory research only.

The name reads as a map of the molecule. “B” is the relaxin-2 B chain, and “7-33” is the stretch of that chain the peptide covers, starting at residue 7 and running to residue 33.

For a lab studying RXFP1, that design is the appeal. Native relaxin-2 switches on two signalling routes at once, so separating their contributions takes extra work. B7-33 leans heavily on one of them, which makes it a reagent for asking narrower questions about how the receptor behaves.

What Is Relaxin-2?

Quick answer: Relaxin-2 is a human peptide hormone in the insulin/relaxin superfamily, which makes it a protein. It has two chains, an A chain and a B chain, joined by disulfide bonds. Its main receptor is RXFP1, also called LGR7, a G protein-coupled receptor. B7-33 keeps part of the B chain, which carries the key receptor-binding residues.

The insulin-like architecture explains both the shape and the problem. Two separate chains have to be made, then linked by three disulfide bonds in the right pairings, and the whole assembly runs to 53 amino acids.

Work on which parts of the molecule touch the receptor pointed at the B chain. Three residues on that chain, two arginines and an isoleucine, carry most of the binding, and no single residue on the A chain was found to control RXFP1 binding at all. That finding is what made a B-chain-only peptide a reasonable thing to attempt.

How Was B7-33 Designed From Relaxin-2?

Quick answer: B7-33 was made by keeping a 7 to 33 residue segment of the relaxin-2 B chain as a single peptide and dropping the A chain, so no inter-chain disulfide bonds are needed. Two cysteines were substituted to prevent unwanted bonding. The result is simpler to synthesize than two-chain relaxin-2 while keeping RXFP1 binding.

Why a single chain?

Two-chain relaxin-2 (53 amino acids, three disulfide bonds) compared with single-chain B7-33 (27 amino acids, none)

Making the two-chain hormone means building both chains, then folding them so that three disulfide bonds form in the correct pairings. Hossain’s group described the native structure as costly and laborious to produce by either chemical or recombinant routes, and the cost of a single-chain peptide is a fraction of it.

Which residues and substitutions?

Six residues came off the N-terminus of the B1-33 segment. Four residues, KRSL, were added at the C-terminus to raise the overall positive charge. The cysteines at positions 11 and 23 were then swapped for serine, an isosteric replacement that stopped the peptide dimerizing and aggregating.

Why sources disagree on length

Several secondary sources describe B7-33 as a 26-amino-acid peptide, including the Wikipedia entry, yet the sequence those same pages print contains 27 residues. Count the sequence in the primary paper and you get 27. Supplier certificates list 27 as well.

How Does B7-33 Interact With RXFP1?

Quick answer: B7-33 binds RXFP1, the same receptor as relaxin-2, with a different signalling profile in cell assays. Hossain et al. (2016) reported that it activates pERK1/2 while producing little cAMP in cells expressing RXFP1, which is why they called it the first functionally selective agonist of this receptor. Its binding affinity is markedly lower than native relaxin-2.

RXFP1 basics

RXFP1 is a G protein-coupled receptor with an unusual front end: a large leucine-rich repeat ectodomain plus an LDLa module, one of only two mammalian GPCRs to carry that module. A 2023 cryo-EM structure of the active receptor bound to Gs (PDB 7TMW) showed extracellular loop 2 occupying the orthosteric pocket, and the authors proposed that the receptor signals through autoinhibition (Erlandson et al., 2023).

LGR7 is the older name for the same receptor and still turns up in earlier literature and in some catalogue listings, so searches for prior work should cover both terms.

pERK1/2 versus cAMP

A receptor can route a signal down more than one path, and a ligand that strongly favours one of them is called biased, or functionally selective. Picture a junction box wired to two circuits: relaxin-2 lights both, while B7-33 mostly lights the pERK1/2 one and leaves cAMP dim.

Agonist bias is the reason B7-33 shows up in method papers as a comparator, in studies where one pathway has to be isolated from the other.

Affinity compared with relaxin-2

In competition binding assays on HEK-293T cells stably expressing human RXFP1, B7-33 gave a pKi of 5.54 against 8.96 for H2 relaxin. The cAMP results tracked the binding data, at pEC50 5.12 for B7-33 against 10.49 for the hormone. Those gaps, over three log units, set the concentration range any assay needs to cover.

What Is B7-33 Used For in Research?

Quick answer: B7-33 is used as a research tool for studying RXFP1 signalling. Typical work includes receptor-binding assays, cAMP and pERK1/2 readouts in RXFP1-expressing cell lines, and side-by-side comparison with native relaxin-2 to study biased agonism. It is not approved for any medical use and is supplied for research use only.

The assay record from the original paper gives a sense of the readouts involved:

Study	Year	Study type	What was measured
Hossain et al., Chemical Science	2016	In vitro, HEK-293T cells expressing human RXFP1	Competition binding, pKi
Hossain et al., Chemical Science	2016	In vitro, HEK-293T cells expressing human, rat or mouse RXFP1	cAMP accumulation, pEC50
Hossain et al., Chemical Science	2016	In vitro, THP-1 cells expressing RXFP1 natively	cAMP response
Hossain et al., Chemical Science	2016	In vitro, HEK-293T cells expressing RXFP1 and rat primary cells	pERK1/2 time course, peak at 3 to 5 minutes
Hossain et al., Chemical Science	2016	In vitro, HEK cells expressing RXFP2	Activity at the related receptor

In vivo pharmacology in rodent models has also been published.

B7-33 activates RXFP1 in cell assays and shows no activation at RXFP2, even at micromolar concentrations

Two points follow from that record for anyone designing an experiment. Native relaxin-2 makes the obvious positive control, since the pair has been characterised side by side in the same cells. And because the potency gap runs to several log units, a concentration range built around relaxin-2 will sit far below the active range for B7-33.

B7-33 vs Relaxin-2 vs Other Relaxin-2 Analogs

Quick answer: B7-33 is one of several relaxin-2 analogs. They differ in structure, from two-chain forms to single-chain and engineered long-acting constructs, and in their signalling profile at RXFP1.

Molecule	Structure	Chains	Receptor	Signalling profile	Development status (October 2026)
Relaxin-2	Native human hormone, 53 residues	Two, three disulfide bonds	RXFP1	cAMP and pERK1/2	Endogenous hormone
Serelaxin	Recombinant relaxin-2	Two	RXFP1	As native relaxin-2	Phase 2 and Phase 3 studies registered on ClinicalTrials.gov; no FDA approval
B7-33	Synthetic B-chain segment, 27 residues	One, no disulfide bonds	RXFP1, inactive at RXFP2	pERK1/2-biased	No registered human studies
AZD3427	Relaxin-2 fused to an IgG1 Fc fragment	Engineered single construct	RXFP1	RXFP1 agonist	Phase 2 completed (NCT05737940); Phase 1 terminated (NCT06611423)
LY3540378	Relaxin analog with an albumin-binding VHH domain	Engineered single construct	RXFP1	RXFP1 agonist	Phase 2 terminated (NCT05592275); second Phase 2 withdrawn (NCT06598631)

Registry statuses were read on ClinicalTrials.gov on 12 October 2026.

What Are the Open Questions About B7-33?

Quick answer: Published B7-33 work is preclinical, and no human studies have been published. Open questions include limited data on its stability in biological matrices, whether its signalling bias holds across cell types and species variants of RXFP1, and a mismatch between sources on its exact length, 26 against 27 residues.

Four gaps stand out for anyone planning experiments:

• Stability: public data on how the peptide behaves in serum or other biological matrices over time is thin, so plan your own stability checks and record the conditions you used.
• Generality of the bias: the pERK1/2 preference was characterised in a specific set of cell backgrounds. Whether it holds in other cells, or at rodent versions of the receptor, is still open.
• Reference data quality: secondary databases carry at least one wrong length and at least one wrong CAS number for this peptide, so the primary paper is the safer source.
• No common reference standard: there is no pharmacopoeial monograph for B7-33, so each supplier’s certificate rests on its own method. Comparing two vendors means comparing two independent reports, with no shared yardstick behind them.

How Should B7-33 Be Verified and Stored?

Quick answer: Check a B7-33 COA for identity by mass spectrometry, where the observed mass should match the expected molecular weight of the sequence, and purity by HPLC, then compare both with the batch result. Store the lyophilized powder cold, dry and away from light, as the label states.

Identity by mass spectrometry

The expected average mass is 2,986.6 Da for the C-terminal amide. The original paper reported an observed m/z of 2,986.4 [M+H]⁺ against a calculated 2,986.59. A report whose observed mass lands a long way from that figure describes a different molecule.

Check the salt form while you are there: a peptide supplied as a TFA salt weighs more than the net peptide in the vial, and certificates state the two separately when the figure has been measured. For the division of labour between the two techniques, see HPLC vs mass spectrometry.

Purity by HPLC

Read the purity by HPLC on the batch result for the specific lot in front of you. For context on what the figures mean in practice, see what 98% vs 99% purity means.

Spotting a fake or edited COA

Check that the report names the lab, carries a batch number and a test date, and can be traced back to the laboratory that issued it. Our guides on how to read a peptide COA and how to check whether a COA is genuine cover the checks in order.

Storage

Keep the sealed, lyophilized vial cold, dry and shielded from light, following the condition printed on the label. The original synthesis describes B7-33 as freely water-soluble, which is useful when preparing solutions for an assay. Our peptide storage guide covers handling of the dry form.

View B7-33 10 mg research peptide

Is B7-33 FDA Approved?

Quick answer: No. As of October 2026, B7-33 is not an FDA-approved drug, and it is sold only as a research chemical for laboratory use. A search of ClinicalTrials.gov on 12 October 2026 returned no registered human studies of B7-33 itself.

Compounding lists are a separate question from approval, and peptides move on and off them through their own process. Our explainer on how FDA compounding lists work sets out the categories and what they mean for a given compound.

B7-33 FAQs

Is relaxin a protein or a steroid?

A protein. Relaxin-2 is a peptide hormone in the insulin/relaxin superfamily, built from two amino acid chains held together by disulfide bonds. Steroids are lipid molecules built on a four-ring carbon skeleton, a completely different class of chemistry.

Is B7-33 the same as relaxin-2?

No. Relaxin-2 is the full two-chain hormone of 53 residues. B7-33 is a 27-residue synthetic peptide taken from part of its B chain, with a lower binding affinity at RXFP1 and a different signalling profile in cell assays.

How many amino acids does B7-33 have?

Several secondary sources say 26, but the sequence those pages display contains 27 residues, and supplier certificates list 27. Count the sequence in Hossain et al. (2016) when the number has to be right.

What does “biased agonist” mean?

A biased agonist binds a receptor and activates one of its downstream signalling routes much more strongly than another. For B7-33 at RXFP1, that means a clear pERK1/2 response alongside a weak cAMP response in the same cells.

Does Life Link Research supply B7-33 with a batch COA?

Yes. Every vial of B7-33 10 mg research peptide ships with a batch-matched certificate from a third-party laboratory, covering identity and purity for that lot.

References

Source	Date	Type
Hossain MA et al. A single-chain derivative of the relaxin hormone is a functionally selective agonist of the G protein-coupled receptor, RXFP1. Chemical Science.	2016	Primary research paper
Bathgate RAD et al. Relaxin family peptides and their receptors. Physiological Reviews.	2013	Review
Erlandson SC et al. The relaxin receptor RXFP1 signals through a mechanism of autoinhibition. Nature Chemical Biology.	2023	Structural study
RCSB Protein Data Bank, entry 7TMW.	2023	Structure record
PubChem, CID 162662592.	Accessed 12 Oct 2026	Chemical database
ClinicalTrials.gov, search for B7-33.	Accessed 12 Oct 2026	Trial registry

For Research Use Only. Not for use in diagnostic or therapeutic procedures. See our terms and research-use policy. Read our full Research Use Disclaimer.