TABLE 2.

Kinetic parameters of purified β-lactamase OXA-54 from S. oneidensis compared to those for OXA-48 from K. pneumoniae 11978a

SubstrateOXA-54OXA-48
kcat (S−1)Km (μM)kcat/Km (M−1 · s−1)kcat (s−1)Km (μM)kcat/Km (M−1 · s−1)
Benzylpenicillin120602245406
Ampicillin5404,3000.1253405,2000.065
Ticarcillin302400.12545550.8
Piperacillin202400.085754100.2
Cephalothin32300.0153200.15
Cephaloridin1450.022270.075
Cefotaxime151,6000.01111900.06
CeftazidimeNDbc45,1000.001
Cefepime11800.00511600.005
Cefpirome41100.03583900.02
Oxacillin35750.525300.85
AztreonamNDND
Imipenem140.252140.15
Meropenem0.11250.0010.12000.0005
  • a Data are the means from three independent experiments. Standard deviations were within 10% of the means. Kinetic data for OXA-48 are from reference 16.

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

  • c —, not determinable.