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-3GlyGlykcat(s−1)221 ± 15b223 ± 2240.1 ± 2.64.5 ± 0.4b14.3 ± 0.8b7.4 ± 1.2b92.3 ± 2b
Km(μM)248 ± 39b9.9 ± 1.33.1 ± 0.3128 ± 17b370 ± 59b464 ± 145b1140 ± 40b
kcat/Km(μM−1s−1)0.8922.512.90.0350.0390.0160.08
pMS402HybridGluGlykcat(s−1)268 ± 5b384 ± 1154.8 ± 5.33.6 ± 0.2b21.6 ± 1.0b11.8 ± 1.4b132 ± 8b
Km(μM)215 ± 17b9.8 ± 0.33.0 ± 0.3118 ± 19b464 ± 60b437 ± 105b1280 ± 120b
kcat/Km(μM−1s−1)1.2539.218.30.0310.0470.0270.10
pMS502HybridGlySerkcat(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
kcat/Km(μM−1s−1)5.418.812.70.361.30.82.7
pMS501IMP-1GluSerkcat(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
kcat/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.