|PDB structures||RCSB PDB PDBe PDBsum|
The peptidyl transferase is an aminoacyltransferase (EC 126.96.36.199) 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. The substrates for the peptidyl transferase reaction are two RNA molecules, one bearing the growing peptide chain and the other bearing the amino acid that will be added to the chain. The peptidyl chain and the amino acids are attached to their respective tRNAs via ester bonds to the O atom at the CCA-3' ends of these tRNAs.
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. Ribozymes are the only enzymes which are not made up of proteins, but ribonucleotides. All other enzymes are made up of proteins. This RNA relic is the most significant piece of evidence supporting the RNA World hypothesis.
- In Prokaryotes, the 50S (23S component) ribosome subunit contains the peptidyl transferase component and acts as a ribozyme. The peptidyl transferase center on the 50S subunit lies at the lower tips (acceptor ends) of the A- and O- site tRNAs.
- In Eukaryotes, 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.
The following protein synthesis inhibitors target peptidyl transferase:
- Chloramphenicol binds to A2451 and A2452 residues in the 23S rRNA of the ribosome and inhibits peptide bond formation.
- Pleuromutilins also bind to peptidyl transferase.
- Macrolide antibiotics are thought to inhibit peptidyl transferase, in addition to inhibiting ribosomal translocation.
- Garret, Grisham, Reginald, Charles. Biochemistry 5th Edition. pp. 437–438.
- Garrett, Grisham, Reginald, Charles. Biochemistry 5th Edition. p. 1062.
- Gu Z, Harrod R, Rogers EJ, Lovett PS (June 1994). "Anti-peptidyl transferase leader peptides of attenuation-regulated chloramphenicol-resistance genes". Proc. Natl. Acad. Sci. U.S.A. 91 (12): 5612–6. doi:10.1073/pnas.91.12.5612. PMC . PMID 7515506.
- Long, Katherine S; Hansen, LH; Jakobsen, L; Vester, B (April 2006). "Interaction of Pleuromutilin Derivatives with the Ribosomal Peptidyl Transferase Center" (PDF). Antimicrobial Agents and Chemotherapy. 50 (4): 1458–1462. doi:10.1128/AAC.50.4.1458-1462.2006. PMC . PMID 16569865.
- Protein synthesis inhibitors: macrolides mechanism of action animation. Classification of agents Pharmamotion. Author: Gary Kaiser. The Community College of Baltimore County. Retrieved on July 31, 2009
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