Table 2.
Catalysis and uncoupling parameters for erythromycin N-demethylation and testosterone 6β-hydroxylation for 3A4-BMR, 3A4-3GLY-BMR, and 3A4-5GLY-BMR.
| Erythromycin N-demethylation | Testosterone 6β-hydroxylation | |||||
|---|---|---|---|---|---|---|
| KM(μM) | Vmax(nmol min−1) | Coupling efficiency%(a) | KM(μM) | Vmax (nmol min−1) | Coupling efficiency%(b) | |
| 3A4-BMR | 20.8 ± 3.6 | 0.0515 ± 0.0004 | 9.4 ± 0.5 | 19.6 ± 2.6 | 0.0066 ± 0.0002 | 3.4 ± 0.1 |
| 3A4-3GLY-BMR | 27.4 ± 4.0 | 0.1177 ± 0.0006 | 10.0 ± 0.8 | 21.3 ± 2.7 | 0.0089 ± 0.0002 | 4.6 ± 0.1 |
| 3A4-5GLY-BMR | 21.3 ± 4.4 | 0.1387 ± 0.0009 | 12.5 ± 0.9 | 19.8 ± 2.2 | 0.0113 ± 0.0003 | 5.8 ± 0.2 |
Coupling parameters are determined at saturating erythromycin (120 μM) and testosterone(150 μM) concentrations. Values are means ± standard deviation of four experiments.
(a)
The coupling efficiency is calculated as: HCHO × 100/NADPH consumed.
(b)
The coupling efficiency is calculated as 6β-hydroxytestosterone × 100/NADPH consumed.