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Trapping and characterization of a reaction intermediate in carbapenem hydrolysis by B. cereus metallo-beta-lactamase. J Am Chem Soc 2008 Nov 26;130(47):15852-63

Date

11/05/2008

Pubmed ID

18980308

Pubmed Central ID

PMC2645938

DOI

10.1021/ja801169j

Scopus ID

2-s2.0-56749177280 (requires institutional sign-in at Scopus site)   71 Citations

Abstract

Metallo-beta-lactamases hydrolyze most beta-lactam antibiotics. The lack of a successful inhibitor for them is related to the previous failure to characterize a reaction intermediate with a clinically useful substrate. Stopped-flow experiments together with rapid freeze-quench EPR and Raman spectroscopies were used to characterize the reaction of Co(II)-BcII with imipenem. These studies show that Co(II)-BcII is able to hydrolyze imipenem in both the mono- and dinuclear forms. In contrast to the situation met for penicillin, the species that accumulates during turnover is an enzyme-intermediate adduct in which the beta-lactam bond has already been cleaved. This intermediate is a metal-bound anionic species with a novel resonant structure that is stabilized by the metal ion at the DCH or Zn2 site. This species has been characterized based on its spectroscopic features. This represents a novel, previously unforeseen intermediate that is related to the chemical nature of carbapenems, as confirmed by the finding of a similar intermediate for meropenem. Since carbapenems are the only substrates cleaved by B1, B2, and B3 lactamases, identification of this intermediate could be exploited as a first step toward the design of transition-state-based inhibitors for all three classes of metallo-beta-lactamases.

Author List

Tioni MF, Llarrull LI, Poeylaut-Palena AA, Martí MA, Saggu M, Periyannan GR, Mata EG, Bennett B, Murgida DH, Vila AJ

Author

Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette University




MESH terms used to index this publication - Major topics in bold

Bacillus cereus
Carbapenems
Cobalt
Electron Spin Resonance Spectroscopy
Hydrolysis
Kinetics
Models, Biological
Protein Structure, Tertiary
Spectrum Analysis, Raman
Stereoisomerism
beta-Lactamases