Catalysis of the peptide bond formation by 50 S subunits of E. coli ribosomes with N-(formyl) methionine ester of adenylic acid as peptide donor.

50 S subunits of E. coli ribosomes catalyze the reaction of the 2'(3')-N-(formyl) methionine ester of adenosine 5'-phosphate and Phe-tRNA resulting in peptide bond synthesis. Cytidine 5'-phosphate stimulates this process on 50 S ribosomal subunits as well as on intact ribosomes. The obtained data show that the areas of the peptidyltransferase donor site which binds the 3'-terminal fragment of peptidyl-tRNA possess completely formed structures on 50 S ribosomal subunits.