Table 3. Steady-state reaction parameters for CTX-M9 and top mutants. K M and k cat were determined via nonlinear Michaelis–Menten fits to steady-state initial velocity data. As predicted from simulations, k cat increased substantially in these mutants. This gain did not come at a cost in catalytic efficiency, as k cat/K M also increased. 95% confidence intervals were calculated via jackknife methods.
| Enzyme | K M | k cat | k cat/K M |
| CTX-M9 | 8.9 μM (8.8–10.6 μM) | 70 s–1 (69–78 s–1) | 7.8 μM–1 s–1 (7.4–7.8 μM–1 s–1) |
| L48A | 12 μM (11.5–13.9 μM) | 156 s–1 (151–165 s–1) | 12 μM–1 s–1 (11.7–13.3 μM–1 s–1) |
| T165W | 5.7 μM (5.4–6.0 μM) | 136 s–1 (134–140 s–1) | 23 μM–1 s–1 (22.8–24.9 μM–1 s–1) |
| S281A | 14 μM (12.2–15.8 μM) | 243 s–1 (236–253 s–1) | 17 μM–1 s–1 (15.7–19.4 μM–1 s–1) |