Peptidyl Transferase

The Peptidyl transferase is an aminoacyltransferase (EC 2.3.2.12) as well as the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis.

Peptidyl transferase activity is carried out by the ribosome. Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. This RNA relic is the most significant piece of evidence supporting the RNA World hypothesis.

• In Bacteria, the 50S (23S component) ribosome subunit contains the peptidyl transferase component and acts as a ribozyme.
• In eukaryotic cells, the 60S (28S component) ribosome subunit contains the peptidyl transferase component and acts as the ribozyme.

Peptidyl transferases are not limited to translation, but there are relatively few enzymes with this function.