Table 2

Kinetic parameters of NDM-8 and NDM-1a

β-LactamNDM-8NDM-1
Km (μM)bkcat (s−1)bkcat/Km (μM−1 s−1)Km (μM)bkcat (s−1)bkcat/Km (μM−1 s−1)
Penicillin G74 ± 1091 ± 31.2029 ± 279 ± 12.70
Ampicillin193 ± 6158 ± 50.82122 ± 12137 ± 51.10
Cephradine52 ± 752 ± 41.0037 ± 463 ± 11.70
Cefoxitin34 ± 13 ± 0.10.1025 ± 64 ± 0.30.05
Cefotaxime30 ± 638 ± 31.3028 ± 445 ± 11.70
Ceftazidime63 ± 312 ± 0.20.2074 ± 932 ± 20.45
Cefepime153 ± 1325 ± 10.17152 ± 3133 ± 50.22
AztreonamNHcNHNHNHNHNH
Imipenem167 ± 846 ± 20.28194 ± 3860 ± 70.31
Meropenem127 ± 20169 ± 121.3054 ± 1066 ± 31.20
  • a The proteins were initially modified by a His tag, which was removed after purification.

  • b Values are means from three independent experiments ± standard deviations.

  • c NH, no hydrolysis was detected under conditions with substrate concentrations up to 1 mM and enzyme concentrations up to 700 nM.