Purification development and characterization of the zinc-dependent metallo-β-lactamase from Bacillus anthracis

Abstract

Metallo-β-lactamase from Bacillus anthracis (Bla2) catalyzes the hydrolysis of β-lactam antibiotics which are commonly prescribed to combat bacterial infections. Bla2 contributes to the antibiotic resistance of this bacterium. An understanding of it is necessary to design potential inhibitors that can be introduced with current antibiotics for effective eradication of anthrax infections. We have purified Bla2 using Ni(2+)-affinity chromatography with over 140-fold increase in activity with a yield of 3.5%. The final specific activity was 19,000 units/mg. Purified Bla2 displays different K ( m ), V ( max ), and (k ( cat ) /K (M)) with penicillin G and cephalexin as substrates and is also sensitive to pH, with maximum activity between pH 7.0-9.0. The IC(50) (50% inhibition concentration) value of EDTA against Bla2 is 630 nM, which can be understood by observing its three-dimensional interaction with the enzyme.