[en] Various cephalosporins, cefoxitin, moxalactam, imipenem and aztreonam were studied as substrates of six class C beta-lactamases. Nitrocefin, cephaloridine, cefazolin, cephalothin and cephalexin were good substrates, with kcat. values ranging from 27 to 5000 s-1. Cefuroxime, cefotaxime and cefoxitin exhibited low kcat. values (0.010-1.7 s-1) and low Km values, which suggested a rate-limiting deacylation. Imipenem and aztreonam were even poorer substrates (kcat. 2 x 10(-4)-3 x 10(-2) s-1) and, in the presence of a reporter substrate, behaved as transient inactivators. With moxalactam, biphasic kinetics were observed, indicating a possible rearrangement of the acyl-enzyme.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Galleni, Moreno ; Université de Liège - ULiège > Département des sciences de la vie > Macromolécules biologiques
Amicosante, G.
Frère, Jean-Marie ; Université de Liège - ULiège > Département des sciences de la vie > Département des sciences de la vie
Language :
English
Title :
A Survey of the Kinetic Parameters of Class C Beta-Lactamases. Cephalosporins and Other Beta-Lactam Compounds