title: Peptidyl transferase activity in rat skeletal muscle ribosomes after protein restriction.
abstract: Rats were fed for 6 consecutive days a diet containing casein supplemented with 3 g/kg methionine. The protein level was either 20% or 3%. Skeletal muscle ribosomes were isolated and the activity of the ribosomal enzyme peptidyl transferase was determined. [3H]puromycin acted as acceptor for tRNA bound peptide provided it was located at the ribosomal peptidyl site. The results showed that the rate of peptidyl transferase activity was 13% lower after protein restriction. The differences amounted to 6% when diphtheria toxin and NAD were added as an inhibitor of elongation factor2. This factor catalyzes translocation of peptidyl-tRNA from ribosomal acceptor to peptidyl site. Between 0.11 and 0.15 pmoles peptidyl-tRNA per pmole ribosome were originally accessable as a substrate for peptidyl transferase. The results indicate that peptidyl transferase contributes to a decrease in protein  synthesis after protein restriction; but that other components also contribute to the decrease observed.
mesh_terms: D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D004167:Diphtheria Toxin / Q000494:pharmacology; D006801:Humans; D007700:Kinetics; D008297:Male; D009132:Muscles / Q000201:enzymology*; D009243:NAD / Q000494:pharmacology; D010445:Peptide Elongation Factors; D010458:Peptidyl Transferases / Q000378:metabolism*; D011488:Protein Deficiency / Q000201:enzymology*; D011691:Puromycin / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D051381:Rats; D012270:Ribosomes / Q000201:enzymology*
chemical_list: D004167:Diphtheria Toxin; D010445:Peptide Elongation Factors; D009243:NAD; D011691:Puromycin; D012343:RNA, Transfer; D000217:Acyltransferases; D010458:Peptidyl Transferases