DD-PEPTIDASES AND BETA-LACTAMASES - CATALYTIC MECHANISMS AND SPECIFICITIES

DD-peptidases and beta-lactamases share several common properties, inc luding the formation of an acylenzyme intermediate in their catalytic pathways. In their interactions with beta-lactam antibiotics, the stab ility of this intermediate is much higher with the peptidases than wit h the beta-lactamases. The structural factors responsible for this dif ference have not been identified. The evolution of beta-lactamases is taking place before our eyes, since mutants are constantly selected wh ich fan hydrolyze the molecules newly introduced as ''beta-lactamase r esistant'' in the chemotherapeutic arsenal.