Table 2.

Kinetic parameters of β-lactamase KLUC-1a

SubstrateRelativeVmaxKm (μM)RelativeVmax/Km
Benzylpenicillin10010100
Amoxicillin653025
Ticarcillin6510
Piperacillin1452070
Cephalothin1,200140100
Cefuroxime1753065
Cefoxitin<0.1NDb ND
Cefotaxime17011020
Ceftazidime0.55,700<0.01
Ceftriaxone1704545
Cefpirome701,9500.5
Cefepime707501
Aztreonam101501
Imipenem0.0130<0.01
  • a V max andV max/Km values were relative to that of benzylpenicillin, for which the values were set equal to 100. Data are the means of three independent experiments. Standard deviations were within 15%.

  • b ND, not determinable.