AAT Bioquest

What is the chemical mechanism by which the peptide bond is formed?

Posted March 21, 2023


Peptide bonds are formed by a reaction in which the amino group of one amino acid joins the carboxyl group of an adjacent neighboring acid. As this occurs, a water molecule is released in the process. This reaction is also considered a dehydration reaction because of the loss of a water molecule.

A peptide bond is formed between the incoming amino acid and growing polypeptide chain. A lone pair of electrons on the nitrogen of the free amino group on the amino acid in the A-site attacks the carboxyl carbon linking the peptide chain to the tRNA in the P-site. Therefore, during peptide bond formation, the nucleophilic attack replaces acyl linkage between the 3’ hydroxyl of the tRNA and the carbonyl carbon with a peptide bond between the carbon and amino nitrogen. The energy used during ATP hydrolysis during tRNA charging is conserved on the ribosome to field peptide bond formation without using any additional energy sources.

Additional resources

Mechanism of peptide bond formation on the ribosome