Table 2.
Steady state kinetic parameters for reduction 2-nitroimidazole substrates by purified His6-tagged nitroreductase candidates
| Nitroreductasea | Compound | k catb (s-1) | KMb (µM) | kcat/KM (mM-1 s-1) |
|---|---|---|---|---|
| NfsA | EF5 | 8.9 ± 0.3 | 160 ± 20 | 56 ± 8 |
| EF3 | 10.7 ± 0.4 | 160 ± 21 | 66 ± 9 | |
| F-misonidazole (F-miso) | 8.8 ± 0.6 | 480 ± 70 | 18 ± 3 | |
| HX-4 | 13.5 ± 0.6 | 180 ± 25 | 75 ± 11 | |
| Pimonidazole (Pimo) | 11.3 ± 0.5 | 240 ± 26 | 47 ± 5 | |
| RB6145 | 2.7 ± 0.2 | 200 ± 33 | 14 ± 2 | |
| NfsB | EF5 | 0.4 ± 0.1 | 1800 ± 840 | 0.2 ± 0.1 |
| EF3 | 1.1 ± 0.5 | 5800 ± 3700 | 0.2 ± 0.1 | |
| F-misonidazole | 2.1 ± 0.1 | 5200 ± 3100 | 0.4 ± 0.3 | |
| HX-4 | 29.5 ± 0.1 | 1100 ± 160 | 26 ± 4 | |
| Pimonidazole, RB6145 | No detectable activity | |||
| AzoR | EF5, EF3, F-miso, HX4, Pimo, RB6145 | No detectable activity | ||
| NemA | EF5, EF3, F-miso, HX4, Pimo, RB6145 | No detectable activity | ||
| Yief | EF5, EF3, F-miso, HX4, Pimo, RB6145 | No detectable activity | ||
| MdaB | EF5, EF3, F-miso, HX4, Pimo, RB6145 | No detectable activity | ||
| WrbA | EF5, EF3, F-miso, HX4, Pimo, RB6145 | No detectable activity |
a: YcdI and KefF were recovered in the insoluble fraction and were not able to be purified;
b: Apparent KM and kcat as determined at 200 mM NADPH.