title: Peptidyl-puromycin synthesis on polyribosomes from Escherichia coli.
abstract: Peptide bond synthesis was studied with native polyribosomes of E. coli. With the use of this system for transpeptidation, it was possible to show that a single K(+) activates the ribosome monomers of polyribosomes; that protonation of a single group (probably imidazole or an N-terminal amino group) with a pK(a) equal to about 7.2 inactivates the transpeptidase complex; that Mn(++) can substitute for Mg(++), but that Ca(++), spermidine, and putrescine do so only very poorly; and that the K(m) for puromycin in this system is about 2.4 x 10(-6) M.
mesh_terms: D000641:Ammonia / Q000494:pharmacology; D001345:Autoradiography; D004926:Escherichia coli / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D010452:Peptide Biosynthesis; D010455:Peptides / Q000032:analysis; D011188:Potassium / Q000494:pharmacology; D011485:Protein Binding; D011691:Puromycin / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*; D012964:Sodium / Q000494:pharmacology; D013696:Temperature; D014316:Tritium
chemical_list: D010455:Peptides; D014316:Tritium; D011691:Puromycin; D000641:Ammonia; D008094:Lithium; D012964:Sodium; D008274:Magnesium; D011188:Potassium