TABLE 2.

Kinetic parameters of purified β-lactamase OXA-143a

Substratekcat (s−1)Km (μM)kcat/Km ratio (s−1 μM−1)
Benzylpenicillin5800.063
Ampicillin77000.01
Ticarcillin13700.003
Piperacillin1400.025
Cephalothin0.22200.001
Oxacillin1.24500.003
Ceftazidime<0.01NDb
Cefotaxime<0.01ND
Cefepime<0.01ND
Cefoxitin<0.01ND
Aztreonam<0.01ND
Imipenem0.0550.01
Meropenem0.31000.003
  • a Data are the means of three independent experiments. Standard deviations were within 10% of the means.

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