TABLE 2.

Kinetic parameters of purified β-lactamase GES-9 compared to those of GES-1 and GES-2

SubstrateGES-9aGES-1bkcat/Km (mM−1 · s−1)GES-2ckcat/Km (mM−1 · s−1)
kcat (s−1)Km (μM)kcat/Km (mM−1 · s−1)
Benzylpenicillin8126707096
Amoxicillin20504006526
Piperacillin351402501323
Cephalothin25085030052112
Cefotaxime>10>1,500ndd152.5
Ceftazidime>50>1,000nd188NDe
Cefepime251,000251.60.6
Aztreonam>300>5,000ndNDND
Imipenem<0.01NDND0.079
  • a Data in this column are means from three independant experiments. Standard deviations were within 10% of the geometric means.

  • b Data in this column are from reference 23.

  • c Data in this column are from reference 26.

  • d nd, not determinable due to too-high Km value.

  • e ND, no detectable hydrolysis (<0.01 s−1).