TABLE 3.
Kinetic parameters determined with the purified OXA-29 β-lactamase
| Substrate | Km (μM)a | kcat (S−1)a | kcat/Km (M−1 s−1) |
|---|---|---|---|
| Oxacillin | 4.4 ± 0.3 | 34 ± 3 | 7.7 × 106 |
| Methicillin | 41 ± 4 | 27 ± 2 | 6.6 × 105 |
| Penicillin G | 10 ± 1 | 65 ± 6 | 6.5 × 106 |
| Ampicillin | 16 ± 1 | 107 ± 10 | 6.7 × 106 |
| Carbenicillin | 16 ± 1 | 13 ± 1 | 8.1 × 105 |
| Piperacillin | 39 ± 3 | 31 ± 3 | 7.9 × 105 |
| Nitrocefin | 96 ± 6 | 1,800 ± 150 | 1.9 × 107 |
| Cefazolin | 30 ± 3 | 11 ± 1 | 3.7 × 105 |
| Cefuroxime | >250 | >0.19 | 7.9 × 102 |
| Cefotaxime | 128 ± 11 | 0.17 ± 0.01 | 1.3 × 103 |
| Ceftazidime | >500 | >0.24 | 4.9 × 102 |
| Aztreonam | 210 ± 17 | 0.21 ± 0.02 | 1.0 × 103 |
| Imipenem | NHb | NH | NH |
| Meropenem | NH | NH | NH |
a
Km and kcat values are the means of three different measurements ± standard deviations.
b
NH, no hydrolysis was detected after 10 min at substrate concentrations up to 0.5 mM and enzyme concentrations up to 235 nM.