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.
Research Article|October 01 1988
A survey of the kinetic parameters of class C β-lactamases. Cephalosporins and other β-lactam compounds
Biochem J (1988) 255 (1): 123-129.
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M Galleni, G Amicosante, J M Frère; A survey of the kinetic parameters of class C β-lactamases. Cephalosporins and other β-lactam compounds. Biochem J 1 October 1988; 255 (1): 123–129. doi: https://doi.org/10.1042/bj2550123
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