Metallo-β-lactamase-catalyzed hydrolysis of cephalosporins: some mechanistic insights into the effect of heterocyclic thiones on enzyme activity

Tamilselvi, A. ; Mugesh, Govindasamy (2011) Metallo-β-lactamase-catalyzed hydrolysis of cephalosporins: some mechanistic insights into the effect of heterocyclic thiones on enzyme activity Inorganic Chemistry, 50 (3). pp. 749-756. ISSN 0020-1669

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Official URL: http://pubs.acs.org/doi/abs/10.1021/ic100253k

Related URL: http://dx.doi.org/10.1021/ic100253k

Abstract

The hydrolysis of β-lactam antibiotics using zinc-containing metallo-β-lactamases (mβl) is one of the major bacterial defense systems. These enzymes can catalyze the hydrolysis of a variety of antibiotics including the latest generation of cephalosporins, cephamycins, and imipenem. It is shown in this paper that the cephalosporins having heterocyclic -SR side chains are less prone to mβl-mediated hydrolysis than the antibiotics that do not have such side chains. This is partly due to the inhibition of enzyme activity by the thione moieties eliminated during hydrolysis. When the enzymatic hydrolysis of oxacillin was carried out in the presence of heterocyclic thiones such as MTT, MDT, DMETT, and MMA, the catalytic activity of the enzyme was inhibited significantly by these compounds. Although the heterocyclic -SR moieties eliminated from the β-lactams upon hydrolysis undergo a rapid tautomerism between thione and thiol forms, these compounds act as thiolate ligands toward zinc(II) ions. The structural characterization of two model tetranuclear zinc(II) thiolate complexes indicates that the -SR side chains eliminated from the antibiotics may interact with the zinc(II) metal center of mβl through their sulfur atoms.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:79293
Deposited On:25 Jan 2012 06:36
Last Modified:25 Jan 2012 06:36

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