Table 2.
Steady-state kinetic parameters for WT-CTX-M-15 and S70A-CTX-M-15 enzymes with corresponding standard deviation (+/−).
| Substrate | β-Lactamase | Vmax (μmol/s) | Km (μM) | kcat (s−1) | kcat/Km (μM−1 s−1) |
|---|---|---|---|---|---|
| Nitrocefin | WT-CTX-M-15 | 3.38 ± 0.12 | 1047.0 ± 75.8 | 338.3 ± 16.4 | 3.23 ± 0.02 |
| S70A-CTX-M-15 | 0.031 ± 0.003 | 45.6 ± 1.38 | 3.15 ± 0.17 | 0.07 ± 0.00 | |
| Ceftiofur | WT-CTX-M-15 | 3.14 ± 0.07 | 330.0 ± 14.1 | 313.7 ± 13.0 | 0.95 ± 0.01 |
| S70A-CTX-M-15 | 0.027 ± 0.00 | 35.0 ± 0.42 | 2.73 ± 0.08 | 0.08 ± 0.00 | |
| Ampicillin | WT-CTX-M-15 | 1.01 ± 0.06 | 197.8 ± 13.0 | 101.9 ± 5.6 | 0.52 ± 0.01 |
| S70A-CTX-M-15 | 0.007 ± 0.00 | 26.4 ± 3.7 | 0.67 ± 0.04 | 0.03 ± 0.00 | |
| DFC | WT-CTX-M-15 | 4.89 ± 0.2 | 141.2 ± 11.2 | 489.8 ± 16.2 | 3.46 ± 0.14 |
| S70A-CTX-M-15 | 0.006 ± 0.00 | 7.8 ± 0.03 | 0.59 ± 0.02 | 0.08 ± 0.00 |