Answer to Question #103428 in Chemistry for Jeevan Jyoti behera

Question

What is the role of ribosomal p-site and a-site in protein biosynthesis? How does streptomycin perform its antibiotic function?

Answer 1

A-site is a binding site of where amino acyl-tRNA enters the ribosome. Here, anticodon triplet of tRNA binds to codon sequence of mRNA, whereas A-site associated ribosome RNA and proteins control the binding. As a result, if the codon-anticodon pair is correct, the aminoacyl tRNA is left in the A-site.

P-site is a site of ribosome where the reaction of transpeptidation occurs. Here, the peptide bond between two amino acid residues or between one amino acid residue and a peptide is formed. The reaction is controlled ribosome RNA near the P-site.

Streptomycin inhibits synthesis of proteins by inhibiting bacteria ribosome functioning. The antibiotic prevents binding of formylmethionine to 16S RNA of the 30S ribosome subunit inhibiting translation initiation.