title: Inactivation of D-alanine carboxypeptidase by penicillins and cephalosporins is not lethal in Bacillus subtilis.
abstract: The D-alanine carboxypeptidase of Bacillus subtilis is a particulate enzyme that is irreversibly inactivated by penicillins and cephalosporins. However, the lethal concentrations of these antibiotics are not the same as those that inhibit enzymatic activity in vitro. 6-Aminopenicillanic acid inactivates at least 95% of the enzyme at nonlethal concentrations. Conversely, cephalothin is lethal at concentrations that do not inactivate the enzyme. Experiments with intact, growing cells confirm the results obtained in vitro. Therefore, a killing site distinct from the carboxypeptidase must be postulated.
mesh_terms: D000409:Alanine; D001412:Bacillus subtilis / Q000201:enzymology*; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors*; D002511:Cephalosporins / Q000494:pharmacology*; D002512:Cephalothin / Q000494:pharmacology; D003023:Cloxacillin / Q000494:pharmacology; D005163:Factor Analysis, Statistical; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010397:Penicillanic Acid / Q000494:pharmacology; D010406:Penicillins / Q000494:pharmacology*; D010457:Peptidoglycan / Q000037:antagonists & inhibitors; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D002511:Cephalosporins; D010406:Penicillins; D010457:Peptidoglycan; D010397:Penicillanic Acid; D002268:Carboxypeptidases; D003023:Cloxacillin; D000409:Alanine; D002512:Cephalothin