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Peptides 101

What is a peptide bond?

Peptides and proteins are chains, and every chain needs links. The link that holds one amino acid to the next is called a peptide bond. Here is how it forms, how it breaks, and why it matters.

4 min read Reviewed for accuracy Research Use Only
The short answer

A peptide bond is the chemical link that joins two amino acids. It is a type of amide bond that forms when the acid group of one amino acid reacts with the amine group of the next, releasing a single water molecule. Peptide bonds are what hold peptides and proteins together.

How a peptide bond forms

Each amino acid has two reactive ends: an amine group and an acid (carboxyl) group. When two amino acids meet, the acid end of one joins the amine end of the other. In doing so, they release one water molecule. Chemists call this a condensation or dehydration reaction.

AA 1 AA 2 bond + H₂O water released (a condensation reaction)
A peptide bond forms when the acid group of one amino acid joins the amine group of the next, releasing one water molecule.

Building chains

Repeat that reaction and the chain grows. Link a handful of amino acids and you have a peptide; link dozens or hundreds and you approach a protein. The repeating pattern of peptide bonds forms what is called the backbone of the molecule.

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How peptide bonds break

Peptide bonds can also be broken, by a reaction called hydrolysis that adds a water molecule back and splits the chain. In living systems, enzymes called proteases do this to recycle amino acids. Understanding how bonds form and break is also key to how peptides are synthesized in the lab.

Key takeaways

  • A peptide bond links two amino acids; it is a type of amide bond.
  • It forms by a condensation reaction that releases one water molecule.
  • Many peptide bonds in a row form the backbone of a peptide or protein.
  • Peptide bonds are broken by hydrolysis, which adds water back.

A note on research use

The peptides supplied by Axis Peptide Labs are reference compounds for laboratory and research use only. They are intended for qualified researchers working in academic, institutional, and analytical settings. They are not drugs, foods, cosmetics, or medical products, and they are not intended for human or veterinary consumption. Documented identity and documented purity are what matter most when sourcing a compound, both of which are published on the Axis certificates of analysis page.

Every compound is tested. Every certificate is public.

Browse the Axis Peptide Labs catalog of third-party tested research peptides, each with a published certificate of analysis.

Axis Peptide Labs supplies reference compounds for laboratory, academic, and institutional research only. All products are for research and identification purposes only. They are not for human or veterinary use, and are not a food, cosmetic, drug, or medical product. This article is educational and does not constitute medical, health, or usage advice.

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