What is a peptidyl transferase?

Peptidyl transferase is a specific type of enzyme that catalyzes the two main chemical reactions of protein synthesis – peptide bond formation and peptide release. During photosynthesis, it catalyzes the addition of an amino acid residue to the growing polypeptide chain by means of peptide bonds. This reaction occurs via nucleophilic displacement.

Peptidyl transferase is located in the larger of the two ribosomal subunits and is composed entirely of RNA. It catalyzes reactions by providing proper substrate orientation, thereby reducing its energy of activation.