Catalytic properties of class A β-lactamases : efficiency and diversity

β-Lactamases are the main cause of bacterial resistance to penicillins, cephalosporins and related β-lactam compounds. These enzymes inactivate the antibiotics by hydrolysing the amide bond of the β-lactam ring. Class A β-lactamases are the most widespread enzymes and are responsible for numerous failures in the treatment of infectious diseases. The introduction of new β-lactam compounds, which are meant to be ‘β-lactamasestable ’ or β-lactamase inhibitors, is thus continuously challenged either by point mutations in the ubiquitous TEM and SHV plasmid-borne β-lactamase genes or by the acquisition of new genes coding for β-lactamases with different catalytic properties.