Table 2.

Kinetic parameters for hydrolysis of various β-lactam antibiotics by the hybrid and parent metallo-β-lactamases

PlasmidEnzymeAmino acid at position:Kinetic parameterAntibiotica
87196LORCEFCTXCAZPENAMPIMP
pMS401IMP-3GlyGly k cat(s−1)221 ± 15b 223 ± 2240.1 ± 2.64.5 ± 0.4b 14.3 ± 0.8b 7.4 ± 1.2b 92.3 ± 2b
Km (μM)248 ± 39b 9.9 ± 1.33.1 ± 0.3128 ± 17b 370 ± 59b 464 ± 145b 1140 ± 40b
k cat/Km (μM−1s−1)0.8922.512.90.0350.0390.0160.08
pMS402HybridGluGly k cat(s−1)268 ± 5b 384 ± 1154.8 ± 5.33.6 ± 0.2b 21.6 ± 1.0b 11.8 ± 1.4b 132 ± 8b
Km (μM)215 ± 17b 9.8 ± 0.33.0 ± 0.3118 ± 19b 464 ± 60b 437 ± 105b 1280 ± 120b
k cat/Km (μM−1s−1)1.2539.218.30.0310.0470.0270.10
pMS502HybridGlySer k cat(s−1)38.4 ± 1.243.2 ± 1.716.5 ± 1.311.3 ± 0.3282 ± 1987.0 ± 2.790.8 ± 5.3
Km (μM)7.1 ± 0.12.3 ± 0.11.3 ± 0.231.8 ± 1.5216 ± 13110 ± 4.933.2 ± 1.9
k cat/Km (μM−1s−1)5.418.812.70.361.30.82.7
pMS501IMP-1GluSer k cat(s−1)62.0 ± 3.065.0 ± 2.922.5 ± 1.916.3 ± 0.9461 ± 17162 ± 15127 ± 11
Km (μM)7.2 ± 0.42.0 ± 0.11.4 ± 0.146.0 ± 1.4241 ± 10140 ± 930.0 ± 3.9
k cat/Km (μM−1s−1)8.632.516.10.351.91.24.2
  • a PEN, benzylpenicillin; see footnoteb of Table 1 for other abbreviations.

  • b Obtained from Michaelis-Menten graph; see Materials and Methods.