Skip to content
Login Register

#peptidyl transferase

3 public questions tagged with this topic.

Translation in Prokaryotes and Eukaryotes

Peptidyl transferase activity resides in

Genetic, biochemical, and crystallographic studies established that peptide bond formation is catalyzed by ribosomal RNA, not protein side chains. The peptidyl transferase center resides within domain V of large subunit 23S rRNA in prokaryotes, conserved as 28S rRNA in eukaryotes, where nucleotides position the 3' CCA ends of P-site and A-site tRNAs for nucleophilic attack of amino group on ester carbonyl. Key adenine A2451 contributes orientation and pKa perturbation rather than direct acid-base chemistry. Deproteinized large subunit retains catalytic activity, demonstrating the ribosome is a true ribozyme, the largest natural RNA catalyst with synthetic polymerase activity known.

Ref: Alberts Molecular Biology of the Cell Fig 6-80; NCBI Bookshelf NBK21760 - peptidyl transferase center composed of 23S rRNA, ribosome is ribozyme

View Details
Translation Basics

Large subunit rRNA catalyzing peptidyl transferase in prokaryotes is

Peptidyl transferase center that catalyzes peptide bond formation resides in large subunit rRNA, not proteins. In prokaryotes, domain V of 23S rRNA folds into catalytic crevice containing conserved A-loop and P-loop positioning CCA ends of A-site and P-site tRNAs for nucleophilic attack of alpha-amino on peptidyl ester. Crystallographic studies reveal no protein within 18 angstroms of active site. Mutation of key 23S adenines abolishes activity while protein removal retains catalysis. Equivalent in eukaryotes is 28S rRNA, confirming ribosome is ribozyme.

Ref: Watson Molecular Biology of the Gene, 7th ed., Chapter 15, 23S rRNA as peptidyl transferase ribozyme

View Details
Acid, Base, pH

Catalysis of peptide bond formation is carried out by

23S/28S rRNA is the scientifically accurate answer to this question. Within the study of Acid, Base, pH, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of 23S/28S rRNA directly address what is being asked. Among the other options, ribosomal proteins, tRNA, and mRNA do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.

Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 2

View Details