title: Alterations in kinetic properties of penicillin-binding proteins of penicillin-resistant Streptococcus pneumoniae.
abstract: Earlier studies have shown that the highly penicillin-resistant South African Strains of pneumococci contain altered penicillin-binding proteins (PBPs) (S. Zighelboim and A. Tomasz, Antimicrob. Agents Chemother. 17:434-442, 1980). We now describe a detailed quantitative characterization of the reaction of radioactively labeled penicillin with the PBPs of the penicillin-susceptible and penicillin-resistant pneumococci and several intermediate-resistance-level genetic transformants as well. The altered binding of the antibiotic by the PBPs of resistant cells appears to be due to a combination of two factors: lower drug affinity and change in the cellular amounts of PBPs. No alteration in the rates of deacylation of the penicilloyl-PBPs of the resistant cells was detected.
mesh_terms: D001426:Bacterial Proteins; D002268:Carboxypeptidases / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism*; D003640:Dealkylation; D004591:Electrophoresis, Polyacrylamide Gel; D006602:Hexosyltransferases; D007700:Kinetics; D002267:Muramoylpentapeptide Carboxypeptidase / Q000378:metabolism*; D010403:Penicillin Resistance; D046915:Penicillin-Binding Proteins; D010406:Penicillins / Q000494:pharmacology*; D010458:Peptidyl Transferases; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010406:Penicillins; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002268:Carboxypeptidases; D002267:Muramoylpentapeptide Carboxypeptidase