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Targeting metallo-carbapenemases via modulation of electronic properties of cephalosporins.
- Source :
-
Biochemical Journal . 12/1/2014, Vol. 464 Issue 2, p271-279. 9p. - Publication Year :
- 2014
-
Abstract
- The global proliferation of metallo-carbapenemase-producing Enterobacteriaceae has created an unmet need for inhibitors of these enzymes. The rational design of metallo-carbapenemase inhibitors requires detailed knowledge of their catalytic mechanisms. Nine cephalosporins, structurally identical except for the systematic substitution of electron-donating and withdrawing groups in the para position of the styrylbenzene ring, were synthesized and utilized to probe the catalytic mechanism of New Delhi metallo-β-lactamase (NDM-1). Under steady-state conditions, Km values were all in the micromolar range (1.5-8.1 μM), whereas kcat values varied widely (17-220 s--1). There were large solvent deuterium isotope effects for all substrates under saturating conditions, suggesting a proton transfer is involved in the rate-limiting step. Pre-steady-state UV-visible scans demonstrated the formation of short-lived intermediates for all compounds. Hammett plots yielded reaction constants (p) of -- 0.34 ± 0.02 and -- 1.15 ± 0.08 for intermediate formation and breakdown, respectively. Temperature-dependence experiments yielded AG* values that were consistent with the Hammett results. These results establish the commonality of the formation of an azanide intermediate in the NDM-1-catalysed hydrolysis of a range cephalosporins with differing electronic properties. This intermediate is a promising target for judiciously designed β - lactam antibiotics that are poor NDM-1 substrates and inhibitors with enhanced active-site residence times. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 02646021
- Volume :
- 464
- Issue :
- 2
- Database :
- Academic Search Index
- Journal :
- Biochemical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 99540628
- Full Text :
- https://doi.org/10.1042/BJ20140364