TABLE 2.

Kinetic constants (Vmax, Km) of β-lactamase produced by K. ascorbata strain CIP 82. 95Ta

SubstrateVmax (relative)Km (μM)Vmax/Km (relative)
Benzylpenicillin10017.5100
Ticarcillin7.51013
Cephalothin1,100141136
Cefuroxime803540
Cefotaxime1103755.1
Ceftazidime<0.150<0.04
Aztreonam0.31050.06
Cefoxitin<0.1110<0.02
  • a Vmax was expressed relative to the Vmax for benzylpenicillin (which was set at 100%).