CAS: 77591-33-4 · MW: 4963.55 Da · Purity: ≥99% by reverse-phase HPLC · Format: 5 mg powder · Identity: ESI-MS confirmed
TB-500 is the research name for a synthetic peptide based on the active, actin-binding region of thymosin beta-4, a natural protein involved in cell movement and tissue repair. Researchers use it to study that repair biology in a smaller, more workable form than the full protein. This is the 5 mg vial, supplied as a reference material for tissue-repair research.
Structure & Identity
TB-500 is a synthetic version of thymosin beta-4, a 43-amino-acid peptide with the sequence Ac-Ser-Asp-Lys-Pro-Thr-Ser-Phe-Asp-Lys-Ser-Lys-Leu-Lys-Lys-Thr-Glu-Thr-Gln-Glu-Lys-Asn-Pro-Leu-Pro-Ser-Lys-Glu-Thr-Ile-Glu-Gln-Glu-Lys-Gln-Ala-Gly-Glu-Ser, carrying a natural acetyl cap on its N-terminus. Its molecular weight is 4963.55 Da and its CAS number is 77591-33-4. The functional heart of the molecule is its central actin-binding region (the LKKTETQ motif), which is where its actin-regulating activity comes from and why “TB-500” is often described in terms of that region.
Research Background
TB-500 research follows the biology of thymosin beta-4, centered on actin and tissue repair.
- Actin regulation. Thymosin beta-4 is best known as an actin-sequestering protein that supports cell migration [PMID: 16099219].
- Regenerative peptide. Reviews describe it as a multifunctional regenerative peptide [PMID: 22074294].
- Active-site fragments. Its activity has been mapped to short peptide sequences within the chain [PMID: 20179146].
- Cardiac models. It has been studied in heart-injury repair research [PMID: 31333080].
- Vasculature. Its roles in blood-vessel development and protection are an active area [PMID: 30063849].
These are research contexts, not approved uses, and the peptide is intended for laboratory study.
Specifications
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Attribute
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Value
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Chemical name
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TB-500 (thymosin beta-4 fragment, actin-binding region)
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Also Known As
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Thymosin Beta-4, Tβ4
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CAS number
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77591-33-4
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Molecular weight
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4963.55 g/mol
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Length
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43 amino acids (acetylated)
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Purity
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≥99% by reverse-phase HPLC
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Identity
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Confirmed by ESI mass spectrometry
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Physical form
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Lyophilized powder
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Appearance
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White to off-white solid
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Quantity
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5 mg per vial
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Storage
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-20°C, protected from light
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Solubility
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Soluble in bacteriostatic or sterile water
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Classification
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Research use only
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Storage & Handling
Store the sealed vial frozen at -20°C, shielded from light, until use. After reconstitution, keep the solution refrigerated at 2-8°C and use it within about two weeks. Warming the vial to room temperature before opening reduces condensation, and avoiding repeated freeze-thaw cycles helps protect the peptide.
Storage and Handling Guide
Quality Assurance
TB-500 is produced under research-grade manufacturing controls and released only after independent verification. Purity is measured by reverse-phase HPLC and identity by mass spectrometry, with that work done by third-party laboratories such as Janoshik Analytical along with domestic US labs. A certificate of analysis is issued for each batch, so the results trace to the exact vial you receive.
Quality & Testing
Frequently Asked Questions
What is TB-500?
TB-500 is a synthetic peptide based on the actin-binding region of thymosin beta-4, a protein tied to cell movement and tissue repair. It is studied in tissue-repair research and is supplied for research use only.
Is TB-500 the same as thymosin beta-4?
Not exactly. TB-500 corresponds to the active fragment of thymosin beta-4, not the full 43-residue protein. Because suppliers vary in how they label this, the exact identity and CAS should be confirmed.
What does TB-500 do in research models?
Research on thymosin beta-4 centers on actin regulation, cell migration, and tissue repair. TB-500 is used to study that biology in a smaller fragment form.
Why is the molecular weight marked “confirm”?
Because “TB-500” is labelled differently by different suppliers (fragment versus full protein), the molecular weight and CAS should be verified against the actual material before publishing.
Is TB-500 FDA approved?
No. TB-500 is not FDA approved. It was reviewed in the 2026 FDA compounding discussion but is not approved. The material here is a research-use-only reference peptide, not for human or veterinary use.
How is TB-500 different from BPC-157?
Both are studied for tissue repair but are different molecules. TB-500 is a thymosin beta-4 fragment; BPC-157 is a gastric-derived pentadecapeptide. They are sometimes studied together.
How should TB-500 be stored?
Keep the powder frozen at -20°C and protected from light. Once reconstituted for research, store at 2-8°C and use within about two weeks.
How is this TB-500 verified?
It is tested to ≥99% purity by reverse-phase HPLC with mass-spec identity confirmation by an independent lab, and each batch has a published certificate of analysis.
References
- Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. 2005. PMID: 16099219.
- Thymosin β4: a multi-functional regenerative peptide. 2012. PMID: 22074294.
- Biological activities of thymosin beta4 defined by active sites in short peptide sequences. 2010. PMID: 20179146.
