Buckwell, Stephen C., Page, Michael I., Waley, Stephen G. and Longridge, Jethro L. (1988) Hydrolysis of 7-substituted cephalosporins catalysed by ?-lactamases I and II from Bacillus cereus and by hydroxide ion. Journal of the Chemical Society, Perkin Transactions 2 (10). pp. 1815-1821. ISSN 1472-779X
Metadata only available from this repository.Abstract
Kinetic parameters are reported for the Bacillus cereus-lactamase I- and -lactamase II-catalysed hydrolysis of a series of thirty-seven cephalosporins substituted in the 7-position. These are compared with the second-order rate constants for the hydroxide ion-catalysed hydrolysis of these derivatives. There is no significant dependence of the rate of the base-catalysed hydrolysis upon the nature of the side-chain substituent. For -lactamase I, kcat/Km varies over 2 × 105 but for -lactamase II the variation with substituents is only 10. For alkyl substituents, kcat/Km increases with chain length and passes through a maximum, for -lactamase I this is with the undecyl derivative and for -lactamase II the octylcephalosporin. For -lactamase I, but not for -lactamase II, the t-butylcephalosporin is a very poor substrate. There is no evidence for a significant cavity in either enzyme to host aromatic residues. An ionised carboxylate residue on the side-chain significantly reduces reactivity with -lactamase I but not -lactamase II. It is suggested that a carboxy group on -lactamase I acts as a general catalyst facilitating -lactam C–N bond fission.
Item Type: | Article |
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Subjects: | Q Science > Q Science (General) Q Science > QD Chemistry |
Schools: | School of Applied Sciences |
Related URLs: | |
Depositing User: | Sharon Beastall |
Date Deposited: | 06 Nov 2009 11:09 |
Last Modified: | 28 Aug 2021 10:52 |
URI: | http://eprints.hud.ac.uk/id/eprint/6124 |
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