Question

Q7. During translation, the role of
enzyme peptidyl transferase is
O a Transfer of phosphate group
D) Peptide bond formation between
adjacent amino acids
0 (c) Amino acid activation
O
(d) Binding of ribosome subunits to
mRNA​

Answer 1

Answer:

The peptidyl transferase is an aminoacyltransferase (EC 2.3.2.12) 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 tRNA 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.[1]:437–8 Peptidyl transferase is an enzyme that catalyzes the addition of an amino acid residue in order to grow the polypeptide chain in protein synthesis.[2] It is located in the large ribosomal subunit, where it catalyzes the peptide bond formation.[3] It is composed entirely of RNA. The alignment between the CCA ends of the ribosome-bound peptidyl tRNA and aminoacyl tRNA in the peptidyl transferase center contribute to its ability to catalyze these reactions.[4] This reaction occurs via nucleophilic displacement. The amino group of the aminoacyl tRNA attacks the terminal carboxyl group of the peptidyl tRNA.[3] 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.[1]:1062

In Eukaryotes, the 60S (28S component) ribosome subunit contains the peptidyl transferase component and acts as the ribozyme.