About peptidyl transferase true is:: (A) Used in elongation and cause attachment of peptide chain to A-site of tRNA, (B) Used in elongation and cause attachment peptide chain to P site, (C) Used in initiation and cause 43S complex formation, (D) Used in initiation and cause 48S complex formation
Answer is A. Ans. A. Used in elongation and cause attachment of peptide chain to A-site of tRNA(Ref: Harper 31/e page 403)The a amino group of the new aminoacyl-tRNA in the A site carries out a nucleophilic attack on the esterified carboxyl group of the peptidyl-tRNA occupying the P site (peptidyl or polypeptide site). At initiation, this site is occupied by the initiator met-tRNAi.This reaction is catalyzed by a peptidyl transferase, a component of the 28S RNA of the 60S ribosomal subunit.This is another example of ribozyme activity.