Galleni M, Frère J M
Laboratoire d'Enzymologie, Université de Liège, Sart Tilman, Belgium.
Biochem J. 1988 Oct 1;255(1):119-22. doi: 10.1042/bj2550119.
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.
已对六种C类β-内酰胺酶与各种青霉素之间的相互作用进行了研究。所有酶的表现都非常一致。苄青霉素的kcat.值相对较低（14 - 75 s-1），但Km值较低导致催化效率较高[kcat./Km = 10×10(6) - 75×10(6) M-1.s-1]。氨苄青霉素的kcat.值低10 - 100倍。羧苄青霉素、苯唑西林、氯唑西林和甲氧西林是非常差的底物，kcat.值在1×10(-3)至0.1 s-1之间。Km值相应较小。可以有把握地推测，对于所有测试的底物，去酰化是限速步骤，导致酰基酶积累。
