Kinetic study of the effect of histidines 240 and 164 on TEM-149 enzyme probed by β-lactam inhibitors.

In the present study, we performed a detailed kinetic analysis of the enzymes TEM-149, TEM-149(H240), and TEM-149(H164-H240) versus a large panel of inhibitors/inactivators, including penicillins, penems, carbapenems, monobactams, cephamycin, and carbacephem. These compounds behaved as poor substrates versus TEM-149, TEM-149(H240), and TEM-149(H164-H240) β-lactamases, and the Ki (inhibition constant), K (dissociation constant of the Henri-Michaelis complex), k+2 and k+3 (first-order acylation and deacylation constants, respectively), and k+2/K values were calculated.