The interaction between six class C beta-lactamases and various penicillins has been studied. All the enzymes behaved in a very uniform manner. Benzylpenicillin exhibited relatively low kcat. values (14-75 s-1) but low values of Km resulted in high catalytic efficiencies [kcat./Km = 10 X 10(6)-75 X 10(6) M-1.s-1]. The kcat. values for ampicillin were 10-100-fold lower. Carbenicillin, oxacillin cloxacillin and methicillin were very poor substrates, exhibiting kcat. values between 1 x 10(-3) and 0.1 s-1. The Km values were correspondingly small. It could safely be hypothesized that, with all the tested substrates, deacylation was rate-limiting, resulting in acyl-enzyme accumulation.
Research Article| October 01 1988
A survey of the kinetic parameters of class C β-lactamases. Penicillins
Biochem J (1988) 255 (1): 119–122.
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M Galleni, J M Frère; A survey of the kinetic parameters of class C β-lactamases. Penicillins. Biochem J 1 October 1988; 255 (1): 119–122. doi: https://doi.org/10.1042/bj2550119
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