Abstract
The mechanism of inhibition of type Ib penicillinase by imipenem (N-formimidoyl thienamycin) and thienamycin was studied. Imipenem and thienamycin. were found to inhibit the penicillinase in a progressive manner, but they differed from one another in the maximum level of enzyme inhibition, even with excess inhibitor. The maximum inhibitions by imipenem and thienamycin amounted to about 50% and 80%, respectively. To elucidate the mechanism of the equilibrium phenomenon, the rate constants in the proposed scheme were estimated. Computerassisted simulation using the rate constants revealed that there is an upper limit to the extents of inactivation by imipenem and thienamycin.
