TABLE 2.

Hydrolysis parameters of KPC-1 and KPC-2 β-lactamases

Substrate or inhibitorkcat (s−1)Relative kcatKm (μM)kcat/Km (μM−1 s−1)Relative kcat/Km
KPC-1aKPC-2KPC-1KPC-2KPC-1KPC-2KPC-1KPC-2KPC-1KPC-2
Substrates
    Cephaloridine3405301001005605000.611.1100100
    Cephalothin7569221353821.40.8423076
    Cefotaxime14224.24.21602200.090.10149.1
    Cefoxitin0.260.310.080.061201800.0020.0020.360.16
    Ceftazidime0.10≤0.120.03≤0.0294NDb0.001ND0.18ND
    Benzylpenicillin32519.69.623271.41.9230170
    Ampicillin11021033401302300.850.9114083
    Cloxacillin25357.46.6100790.250.444140
    Imipenem12153.72.881510.150.292626
    Meropenem3.04.00.90.7512150.250.274125
    Aztreonam20305.95.73103600.070.08117.6
Inhibitors
    Clavulanic acidc1.21.5
    Tazobactamc0.230.18
    EDTA>5,000>5,000
  • a KPC-1 kcat and Km data are from reference 47.

  • b ND, not determined.

  • c Inhibitor constant (Ki) is micromolar.