Peptidiltranszferáz

Peptidiltranszferáz is an enzyme that plays a crucial role in protein synthesis. Specifically, it catalyzes the formation of peptide bonds between amino acids during the translation process. This enzyme is an integral part of the ribosome, the cellular machinery responsible for building proteins. The active site of the peptidiltranszferáz is located within the large ribosomal subunit.

The mechanism involves the transfer of an amino acid from a transfer RNA (tRNA) molecule bound to the A-site of the ribosome to an amino acid attached to a tRNA molecule in the P-site. This linkage creates a new peptide bond, elongating the polypeptide chain. The energy for this reaction is derived from the high-energy ester bond linking the amino acid to its tRNA.

In eukaryotes and archaea, the peptidiltranszferáz activity is primarily carried out by ribosomal RNA (rRNA), classifying it as a ribozyme. This discovery challenged the traditional understanding that only proteins could act as enzymes. In bacteria, the catalytic activity is also attributed to rRNA. The importance of peptidiltranszferáz is highlighted by its essential role in life and its targeted inhibition by certain antibiotics, such as macrolides and tetracyclines, which disrupt bacterial protein synthesis. Understanding its function is key to comprehending the fundamental process of gene expression.