title: [Nature of the inhibition of some cephalosporinases by carbenicillin].
abstract: This paper deals with the kinetic inhibition of six cephalosporinases (cephalosporin amido-beta-lactamhydrolase, EC 3.5.2.8) by carbenicillin. In previous cases, the inhibition has appeared usually to be competitive and slowly reversible. This makes it possible to measure the two terms of the ratio Ki=k5/k4;k4 and k5 being respectively the velocity constants of formation and destruction of the enzyme-inhibitor complex. A program was prepared which made it possible to obtain these constants from only one experiment. With ampicillin and cloxacillin, we verified that the reaction is faster, and that only Ki can be measured. These facts suggest that special precautions should be taken in order to obtain signigicant values for the constants governing inhibition.
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D000667:Ampicillin / Q000494:pharmacology; D001419:Bacteria / Q000201:enzymology; D002228:Carbenicillin / Q000494:pharmacology*; D003023:Cloxacillin / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors; D007700:Kinetics; D008433:Mathematics; D065093:beta-Lactamase Inhibitors
chemical_list: D007527:Isoenzymes; D065093:beta-Lactamase Inhibitors; D000667:Ampicillin; D000581:Amidohydrolases; D002228:Carbenicillin; D003023:Cloxacillin
vernacular_title: Nature de l'inhibition de céphalosporinases par la carbénicilline