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A thiono-beta-lactam substrate for the beta-lactamase II of Bacillus cereus. Evidence for direct interaction between the essential metal ion and substrate.

ABSTRACT: An 8-thionocephalosporin was shown to be a substrate of the beta-lactamase II of Bacillus cereus, a zinc metalloenzyme. Although it is a poorer substrate, as judged by the Kcat./Km parameter, than the corresponding 8-oxocephalosporin, the discrimination against sulphur decreased when the bivalent metal ion in the enzyme active site was varied in the order Mn2+ (the manganese enzyme catalysed the hydrolysis of the oxo compound but not that of the thiono compound), Zn2+, Co2+ and Cd2+. This result is taken as evidence for kinetically significant direct contact between the active-site metal ion of beta-lactamase II and the beta-lactam carbonyl heteroatom. No evidence was obtained, however, for accumulation of an intermediate with such co-ordination present.

SUBMITTER: Murphy BP

PROVIDER: S-EPMC1138430 | biostudies-other | 1989 Mar

REPOSITORIES: biostudies-other

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Identification of beta-lactamase in antibiotic-resistant Bacillus cereus spores.

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X-ray absorption spectroscopy of metal site speciation in the metallo-β-lactamase BcII from Bacillus cereus.

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Comparison of beta-lactamase II from Bacillus cereus 569/H/9 with a beta-lactamase from Bacillus cereus 5/B/6.

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beta-lactamase I from Bacillus cereus. Structure and site-directed mutagenesis.

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Separation, purification and properties of beta-lactamase I and beta-lactamase II from Bacillus cereus 569/H/9.

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