CHARACTERIZATION OF A BETA-LACTAMASE FROM MYCOBACTERIUM-SMEGMATIS SN2

Beta-lactamases have been reported to be largely responsible for beta- lactam resistance in Mycobacteria. We report the characterization of a cell-associated beta-lactamase from Mycobacterium smegmatis. The enzy me hydrolyzed the ''beta-lactamase-stable'' oximinocephalosporins. Nit rocefin was the best substrate. 6-Beta-iodopenicillanate, clavulanate and sulbactam were effective inhibitors, whereas the K-i value aztreon am was high. From its substrate and inhibitor, the enzyme appeared to be a cephalosporinase of group 2e.