Determination of thermodynamic parameters of benzylpenicillin hydrolysis by metallo-β-lactamase CcrA from Bacteroides fragilis

One of the most common way that bacteria become resistant to antibiotics is by the production of metallo-β-lactamases (MβLs) to hydrolyze the β-lactam-containing antibiotics. In this paper, the thermodynamic parameters of benzylpenicillin hydrolysis with B1 subclasses MβL CcrA (carbapenem and cephamycin resistance) from Bacteroides fragilis were determined by microcalorimetry. The activation free energy Δ G ≠ θ is 87.90 ± 0.03, 88.99 ± 0.01, 89.93 ± 0.04 and 90.93 ± 0.05 kJ mol−1 at 293.15, 298.15, 303.15 and 308.15 K, activation enthalpy Δ H ≠ θ is 29.21 ± 0.03 kJ mol−1, activation entropy Δ S ≠ θ is −200.34 ± 0.08 J mol−1 K−1, the reaction order is 1.4, and the apparent activation energy E is 31.71 kJ mol−1. The thermodynamic characterization indicated that CcrA prefer to hydrolyze penicillins among three kinds of β-lactam-containing antibiotics.