TABLE 2.
Kinetic constants of NDM mutants toward five β-lactams
| Drug | Constant | Result for: |
|||||
|---|---|---|---|---|---|---|---|
| WT | Mutant |
||||||
| V67G | W87A | Q119D | K224A | N233A | |||
| Ampicillin | Km (μM) | 270 ± 53 | 1,169 ± 322 | NDa | 170 ± 44 | ND | 266 ± 50 |
| kcat (s−1) | 834 ± 86 | 1,807 ± 399 | ND | 117 ± 13 | ND | 625 ± 62 | |
| kcat/Km (μM−1 s−1) | 3.09 | 1.55 | ND | 0.69 | ND | 2.35 | |
| Cefepime | Km (μM) | 319 ± 44 | ND | 538 ± 147 | 180 ± 39 | ND | 149 ± 39 |
| kcat (s−1) | 28 ± 2 | ND | 0.4 ± 0.1 | 3.8 ± 0.4 | ND | 1.2 ± 0.2 | |
| kcat/Km (μM−1 s−1) | 0.09 | ND | 0.00 | 0.02 | ND | 0.01 | |
| Meropenem | Km (μM) | 73 ± 17 | ND | ND | 32 ± 7 | ND | ND |
| kcat (s−1) | 398 ± 44 | ND | ND | 32 ± 2 | ND | ND | |
| kcat/Km (μM−1 s−1) | 5.45 | ND | ND | 1.00 | ND | ND | |
| Imipenem | Km (μM) | 313 ± 94 | 680 ± 279 | ND | 90 ± 15 | ND | 687 ± 327 |
| kcat (s−1) | 278 ± 54 | 576 ± 186 | ND | 42 ± 3 | ND | 45 ± 17 | |
| kcat/Km (μM−1 s−1) | 0.89 | 0.85 | ND | 0.47 | ND | 0.07 | |
| Ertapenem | Km (μM) | 121 ± 15 | 264 ± 56 | ND | 19 ± 2 | ND | 84 ± 27 |
| kcat (s−1) | 118 ± 8 | 224 ± 34 | ND | 4 ± 0 | ND | 16 ± 3 | |
| kcat/Km (μM−1 s−1) | 0.98 | 0.85 | ND | 0.21 | ND | 0.19 | |
a
ND, the kinetic constants could not be determined due to the low activity of the mutations.