Table 3

Steady-state kinetic parameters of purified FIM-1 enzymes

SubstrateaSteady-state kinetic parametersb
FIM-1NDM-1VIM-2IMP-1
kcat (s−1)Km (μM)kcat/Km (M−1 s−1)kcat (s−1)Km (μM)kcat/Km (M−1 s−1)kcat (s−1)Km (μM)kcat/Km (M−1 s−1)kcat (s−1)Km (μM)kcat/Km (M−1 s−1)
Ampicillin*1508.31.8 × 10715226.6 × 105125901.4 × 1069502004.8 × 106
Piperacillin420361.2 × 10714121.2 × 1053001252.4 × 1067.2 × 105
Temocillin>0.3>2001.5 × 1037.73902.0 × 104>2,000<100
Cefoxitin571165.0 × 1051492.0 × 10415131.2 × 1061682.0 × 106
Ceftazidime>80>2004.0 × 10551812.8 × 1043.6725.0 × 1048441.8 × 105
Cefepime>25>2001.2 × 10513771.7 × 105>40>4001.0 × 1057116.6 × 105
Imipenem1535.13.0 × 10720942.1 × 1053493.8 × 10646391.2 × 106
Meropenem*192.28.6 × 10612492.5 × 105522.5 × 1065105.0 × 105
Ertapenem*80.51.6 × 10716217.6 × 105
  • a *, The Km was obtained with an inhibition assay using cefoxitin at 200 μM as the reporter substrate; †, pseudo-first-order kinetics in the range of the tested concentrations were observed with these substrates.

  • b For FIM-1, the individual kinetic parameters are means of three measurements; the standard deviations were always <10% (except for temocillin, ≤20%). The data for NDM-1, VIM-2, and IMP-1 are from references 36, 22, and 27, respectively. –, Data not available.