The peptide bond is the building block behind every peptide and every protein. In this short, clear guide we explain what a peptide bond is, how it forms and why it matters so much in biochemistry — the foundation beneath all peptide research.
A peptide bond is the covalent amide bond between the carboxyl group of one amino acid and the amino group of the next. It forms through a condensation reaction that releases water, and it forms the backbone of every peptide and protein.
What is a peptide bond?
A peptide bond is the covalent amide bond that joins two amino acids into a chain. It is exactly this bond that turns loose amino acids into a peptide. Want the bigger picture first? Read what peptides are.
How does a peptide bond form?
A peptide bond forms through a condensation reaction: the carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH2) of the next, releasing one molecule of water. That reaction is also called dehydration synthesis, because water is split off. The result is a stable C-N bond that firmly joins the two amino acids. How those bonds are built up one by one in the lab is explained in solid-phase peptide synthesis.
Why does the peptide bond matter so much?
The peptide bond forms the backbone of every peptide and protein, and therefore sets the order — the sequence — of the amino acids. A peptide of n amino acids contains n-1 peptide bonds. Why does that order count? Because the sequence is exactly what determines a peptide's properties, and with it why researchers study one specific peptide. See the full catalogue of research peptides.
Can a peptide bond be broken again?
Yes: the reverse reaction is called hydrolysis, where water splits the peptide bond again. In biological systems this happens under the influence of enzymes called peptidases. That balance between formation (condensation) and breakdown (hydrolysis) is a core theme in biochemistry. Read more about how we characterise peptides on the science page.
This information is general and educational in nature. LYSENTA supplies research peptides for laboratory and research purposes only. Not for human or animal consumption, not a medicine and not medical advice.
Frequently asked questions about the peptide bond
What is a peptide bond?
A peptide bond is the covalent amide bond that joins two amino acids. It forms between the carboxyl group of one amino acid and the amino group of the next, releasing a molecule of water.
How does a peptide bond form?
A peptide bond forms through a condensation (dehydration) reaction: the carboxyl group (-COOH) of one amino acid reacts with the amino group (-NH2) of the next, and one water molecule (H2O) is released.
What is the difference between a peptide and a peptide bond?
A peptide is the chain of amino acids; the peptide bond is the specific chemical bond joining two consecutive amino acids in that chain. A peptide of n amino acids therefore contains n-1 peptide bonds.
Can a peptide bond be broken again?
Yes. The reverse reaction is called hydrolysis: adding water splits the peptide bond and the amino acids come apart again. In the body this happens under the influence of enzymes (peptidases).
