Different transition-state structures for the reactions of beta-lactams and analogous beta-sultams with serine beta-lactamases

Beta-sultams are the sulfonyl analogues of beta-lactams and N-acyl beta-sultams are novel inactivators of the class C beta-lactamase of Enterobacter cloacae P99. The analogous N-acyl beta-lactams undergo enzyme-catalyzed hydrolysis, the rate of which is compatible with significant amide anion expulsion/S-N fission in the transition state, and the enzyme reaction displays a later transition compared with hydrogen-ion-catalyzed hydrolysis of the beta-sultam.