Table 5.

Metal/enzyme ratios and catalytic efficiencies of the metallo-β-lactamase at different pH valuesa

pHBuffer[Zn]/[enzyme]kcat/Km (μM−1 s−1)
5Acetate1.8 ± 0.20.8
5Citrate0.3 ± 0.1<0.01
6Cacodylate1.9 ± 0.21
6.5Cacodylate1.8 ± 0.21.2
7Cacodylate1.9 ± 0.21.2
7.5HEPES1.7 ± 0.21.2
8HEPES1.8 ± 0.20.5
  • a The substrate was imipenem.