Table 4.

Kinetic parameters of various β-lactam antibiotics for the Sed-1 β-lactamase from C. sedlakii 2596

Substratekcat (s−1)Km(μM)kcat/Km(s−1 · mM−1)IC50 (μM)
Benzylpenicillin300 ± 345 ± 26,650 ± 230
Ampicillin240 ± 20565 ± 75425 ± 30
Ticarcillin25 ± 140 ± 4625 ± 50
Piperacillin20 ± 0.05165 ± 1120 ± 0.04
Cephalothin180 ± 0.330 ± 26,000 ± 30
Cefoxitin<0.01NDb ND16
Cefuroxime65 ± 520 ± 0.33,250 ± 100
Cefotaxime80 ± 5170 ± 20470 ± 40
Ceftazidime5 ± 0.12,380 ± 2002 ± 0.1
Aztreonam30 ± 3390 ± 8075 ± 8
Cefpirome215 ± 151,000 ± 100215 ± 15
Oxacillin85 ± 8340 ± 60255 ± 20
Cloxacillin165 ± 8130 ± 101,270 ± 40
Imipenem<0.01NDND
Clavulanic acid0.065
Sulbactam2.5
  • a Mean ± standard deviation values are indicated.

  • b ND, not determined.