AN OVERVIEW OF THE KINETIC-PARAMETERS OF CLASS-B BETA-LACTAMASES

The catalytic properties of three class B beta-lactamases (from Pseudo monas maltophilia, Aeromonas hydrophila and Bacillus cereus) were stud ied and compared with those of the Bacteroides fragilis enzyme. The A. hydrophila beta-lactamase exhibited a unique specificity profile and could be considered as a rather specific 'carbapenemase'. No relations hips were found between sequence similarities and catalytic properties . The problem of the repartition of class B beta-lactamases into sub-c lasses is discussed. Improved purification methods were devised for th e P. maltophilia and A. hydrophila beta-lactamases including, for the latter enzyme, a very efficient affinity chromatography step on a Zn2-chelate column.