Peptide Bonds
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What is a Peptide Bond?
At Life Link Research, we maintain rigorous standards to ensure our peptides surpass 99% purity, employing advanced solution and solid-phase peptide synthesis technologies. This meticulous approach allows us to provide peptides and proteins of superior quality, tailored to diverse research applications.
To uphold peptide purity, our processes are carefully controlled to eliminate unwanted impurities and preserve the correct amino acid sequence in the final products. We implement stringent quality control measures to monitor synthesis conditions and promptly address any deviations, safeguarding the integrity of the production process.
Our verification methods include High-Performance Liquid Chromatography (HPLC), which separates components based on their interactions with the chromatographic column, enabling precise determination of purity levels. Additionally, Mass Spectrometry (MS) is utilized to confirm peptide molecular weight and composition, ensuring synthesized peptides match expected profiles accurately.
By integrating cutting-edge synthetic technologies and analytical methods, Life Link Research guarantees peptides that meet the highest purity and quality standards, catering to diverse scientific research requirements.
Peptide Bond Formation
Peptide bond formation requires the proper orientation of amino acid molecules, enabling the carboxylic acid group of one amino acid to react with the amine group of another, forming a peptide bond. This fundamental process is illustrated when two lone amino acids combine to create a dipeptide, the smallest peptide composed of only two amino acids.
Moreover, amino acids can link together in chains to form various peptides. Typically, those containing 50 or fewer amino acids are termed peptides, while those with 50 to 100 amino acids are referred to as polypeptides. Larger peptides with over 100 amino acids are generally classified as proteins. For detailed distinctions between peptides, polypeptides, and proteins, refer to our peptide glossary.
Peptide bonds formed within peptides, polypeptides, and proteins are susceptible to hydrolysis, a chemical breakdown resulting from water contact. Although the reaction is slow, it releases approximately 10 kJ/mol of free energy. Notably, enzymes in living organisms can catalyze both the formation and breakdown of peptide bonds. Many biologically active compounds, such as hormones, antibiotics, antitumor agents, and neurotransmitters, are peptides, often referred to as proteins due to their amino acid content.
Structure of the Peptide Bond
X-ray diffraction studies conducted on small peptides have provided insights into the physical characteristics of peptide bonds. These investigations reveal that peptide bonds exhibit rigidity and planarity. These traits primarily stem from the resonance interaction of the amide group, where the amide nitrogen delocalizes its lone pair of electrons into the carbonyl oxygen.
This resonance profoundly influences the structure of the peptide bond. Notably, the N–C bond within the peptide bond is shorter than the N–Cα bond, while the C=O bond is longer than typical carbonyl bonds. Furthermore, in peptides, the carbonyl oxygen and amide hydrogen adopt a trans configuration rather than a cis configuration. This trans configuration is energetically favored due to the potential steric interactions associated with a cis configuration
The Polarity of the Peptide Bond
In a peptide bond, free rotation around a single bond between a carbonyl carbon and amide nitrogen is typically expected. However, the presence of a lone pair of electrons on the nitrogen near a carbon-oxygen bond introduces a resonance effect. This results in a reasonable resonance structure where a double bond forms between the carbon and nitrogen. Consequently, the oxygen carries a negative charge, while the nitrogen bears a positive charge. This resonance structure restricts rotation around the peptide bond. Moreover, the actual structure is a weighted hybrid of these resonance structures, with the peptide bond exhibiting approximately 40% double-bond character, rendering it rigid.
The charges associated with this resonance result in a permanent dipole within the peptide bond. Specifically, the oxygen carries a -0.28 charge, while the nitrogen holds a +0.28 charge, contributing to the overall polarity of the peptide bond.