Exploring antibiotic resistant mechanism by microcalorimetry.

In an effort to probe the reaction of antibiotic hydrolysis catalyzed by B3 metallo-β-lactamase (MβL), the thermodynamic parameters of penicillin G hydrolysis catalyzed by MβL L1 from Stenotrophomonas maltophilia were determined by microcalorimetric method. The values of activation free energy Δ G are 88.26, 89.44, 90.49, and 91.57 kJ mol at 293.15, 298.15, 303.15, and 308.15 K, respectively, activation enthalpy Δ H is 24.02 kJ mol, activation entropy Δ S is −219.2511 J mol K, apparent activation energy E is 26.5183 kJ mol, and the reaction order is 1.0. The thermodynamic parameters reveal that the penicillin G hydrolysis catalyzed by MβL L1 is an exothermic and spontaneous reaction. [ABSTRACT FROM AUTHOR]