Peptidyltransferase is an example of?

ANSWER: (D) RibozymeREF: With text"Most enzymatic processes, then, were eventually surrendered to the proteins--but not all. The enzymatic activity that catalyzes peptide bond formation has historically been referred to as peptidyl transferase and was widely assumed to be intrinsic to one or more of the proteins in the large ribosomal subunit. We now know that this reaction is catalyzed by the 23S rRNA, adding to the known catalytic repertoire of ribozymes: REF: Lehninger Principles of Biochemistry, 4th Edition, page 1058"The Peptidyl transferase is an aminoacyltransferase as well as the primary enzymatic function of the ribosome, which forms peptide links between adjacent amino adds 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" (REF: http://en.wikipedia.org/wiki/Peptidyl_transferase)"The formation of a peptide bond between two amino acids, one present on the P site and the other on the A site, takes place with the help of an enzyme peptidyl transferase" (REF: Biochemistry - Keshav Trehan 2nd edition Page 186)