TABLE 2.
Kinetic data for the pure DHA-1, DHA-6, and DHA-7 β-lactamases
| Antibiotic and kinetic parameter | Data (mean± SD) for: |
||
|---|---|---|---|
| DHA-1 | DHA-6 | DHA-7 | |
| Nitrocefin | |||
| Km (μM) | 84 ± 8 | 279 ± 17 | 88 ± 11 |
| kcat (s−1) | 1,537 ± 120 | 2,319 ± 420 | 797 ± 67 |
| kcat/Km (μM−1s−1) | 18.297 | 8.311 | 9.056 |
| Ampicillin | |||
| Km (μM) | 0.877 ± 0.342 | 0.925 ± 0.088 | 1.466 ± 0.397 |
| kcat (s−1) | 1.346 ± 0.226 | 1.9 ± 0.26 | 1.475 ± 0.095 |
| kcat/Km (μM−1s−1) | 1.534 | 2.05 | 1.006 |
| Cephalothin | |||
| Km (μM) | 39.21 ± 16.33 | 66.39 ± 23.23 | 35.586 ± 15.66 |
| kcat (s−1) | 179 ± 23 | 198 ± 7 | 222 ± 2 |
| kcat/Km (μM−1s−1) | 4.565 | 2.98 | 6.23 |
| Cefotaxime | |||
| Km (μM) | 0.0824 ± 0.005 | 0.153 ± 0.021 | 0.0927 ± 0.002 |
| kcat (s−1) | 0.0907 ± 0.01 | 0.125 ± 0.02 | 0.177 ± 0.024 |
| kcat/Km (μM−1s−1) | 1.1 | 0.816 | 1.9 |
| Ceftazidime | |||
| Km (μM) | 207.07 ± 54 | 106.74 ± 22.74 | 240 ± 72 |
| kcat (s−1) | 1.748 ± 0.192 | 0.708 ± 0.115 | 2.003 ± 0.22 |
| kcat/Km (μM−1s−1) | 0.0084 | 0.0063 | 0.0083 |
| Cefoxitin | |||
| Km (μM) | 0.265 ± 0.137 | 0.256 ± 0.066 | 0.25 ± 0.127 |
| kcat (s−1) | 0.04349 ± 0.007 | 0.0486 ± 0.008 | 0.0412 ± 0.007 |
| kcat/Km (μM−1s−1) | 0.163 | 0.189 | 0.1648 |
| Clavulanic acid (IC50 [μM]) | 806 ± 394 | 361 ± 25 | 483 ± 279 |
| Sulbactam (IC50 [μM]) | 3.17 ± 0.23 | 2.99 ± 0.32 | 3.97 ± 0.21 |
| Tazobactam (IC50 [μM]) | 0.143 ± 0.007 | 0.124 ± 0.007 | 0.267 ± 0.044 |