title: The inactivation of beta-lactamase I from B. Cereus by dicloxacillin: effect of buffer composition on the kinetic characteristics of the modified enzyme.
abstract: Buffer composition affects the pattern of inactivation of B. cereus beta-lactamase I by dicloxacillin. At pH 7.0, in the presence of phosphate ions, dicloxacillin appears to cause essentially an irreversible inactivation of the catalytic site of the enzyme, while in a tris-cacodylate buffer the inactivation process appears to affect essentially the substrate-binding site. Buffer ions act presumably by interacting themselves with either the catalytic or the substrate-binding site of the enzyme, thus modifying the affinity of these sites for the halogenated isoxazolyl-penicillins.
mesh_terms: D001409:Bacillus cereus / Q000201:enzymology*; D001665:Binding Sites; D001667:Binding, Competitive; D002101:Cacodylic Acid / Q000494:pharmacology; D004009:Dicloxacillin / Q000494:pharmacology*; D007700:Kinetics; D009994:Osmolar Concentration; D010710:Phosphates / Q000494:pharmacology; D014325:Tromethamine / Q000494:pharmacology; D065093:beta-Lactamase Inhibitors
chemical_list: D010710:Phosphates; D065093:beta-Lactamase Inhibitors; D014325:Tromethamine; D002101:Cacodylic Acid; D004009:Dicloxacillin