AAT Bioquest

What are the characteristics of peptide bonds?

Posted March 21, 2023


A peptide bond is defined as a covalent bond that joins two amino acids together to create a protein. Peptide bonds are amide bonds that form when the nitrogen atom of one amino acid links with the carbon atom of a different amino acid. This reaction generates a new carbon-nitrogen double bond and releases a water molecule. This reaction is known as a dehydration reaction. Peptide bonds exhibit a partial double bond characteristic due to its bond resonance. Resonance structures form due to the interaction between the carbonyl groups’ double bond electrons and the electrons of the C-N bond. Peptide bonds are durable, highly kinetically stable, and high activation energies are required in order to break its bonds. Peptides are rigid and planar, and therefore rotation is very limited to near none;. This allows for the peptide bond to remain fixed in a cis or trans configuration. The trans configuration of peptide bonds creates less steric hindrances of amino acid molecules. Additionally, the C=O and N-H bonds are polar, and thus different areas of the peptide allow for hydrogen bonding. The C=O bond is longer than a regular C=O bond due to this resonance. In contrast, the partial double bonded C-N is shorter than a regular C-N single bond is. 

Additional resources

Biochemistry, Peptide