TABLE 2

Kinetic parameters of NDM-17 and NDM-5 enzymesa

β-LactamNDM-17bNDM-5bkcat/Km ratio (μM−1 s−1) for NDM-17/NDM-5
Mean Km (μM) ± SDMean kcat (s−1) ± SDkcat/Km ratio (μM−1 s−1)Mean Km (μM) ± SDMean kcat (s−1) ± SDkcat/Km ratio (μM−1 s−1)
Ampicillin586 ± 53157 ± 110.27590 ± 57267 ± 8.10.450.60
AztreonamNHNHNHNHNHNHNH
Cefepime81 ± 5.57.5 ± 1.760.092102 ± 7.911 ± 2.80.110.83
Cefotaxime11 ± 2.511 ± 3.91.0022 ± 5.421 ± 5.90.951.05
Cefoxitin23 ± 3.15.2 ± 0.040.2345 ± 0.816.6 ± 0.470.151.53
Ceftazidime82 ± 8.610 ± 1.10.12155 ± 1621 ± 0.760.140.86
Ertapenem237 ± 2549 ± 2.60.21571 ± 20120 ± 7.50.211.00
Imipenem188 ± 0.2879 ± 2.50.42396 ± 4.3148 ± 0.640.371.14
Meropenem453 ± 33127 ± 150.28659 ± 36222 ± 480.340.82
Penicillin G365 ± 33115 ± 130.32660 ± 2193 ± 160.142.29
  • a The proteins were initially modified with a His tag, which was removed after purification.

  • b Km and kcat values are means ± standard deviations from three independent experiments. NH denotes no hydrolysis under conditions with substrate concentrations of up to 1 mM and enzyme concentrations of up to 700 nM.