Kinetic parameters of acenocoumarol and warfarin hydroxylations catalyzed by recombinant human cytochrome P450 enzymes
| P450 | Substrate | Metabolite | Km | Vmax | Vmax/Km |
|---|---|---|---|---|---|
| μM | pmol · min−1 · nmol−1CYP | μl · min−1 · nmol−1 CYP | |||
| CYP2C9 | (R)-AC2-a | 6-OH | 9.2 ± 0.6 | 40.5 ± 7.4 | 3.7 ± 2.0 |
| 7-OH | 12.0 ± 0.7 | 59.0 ± 2.5 | 4.2 ± 1.2 | ||
| 8-OH | 10.7 ± 2.0 | 6.5 ± 1.0 | 0.7 ± 0.2 | ||
| (S)-AC | 6-OH | 2.6 ± 0.05 | 350 ± 22 | 137 ± 12 | |
| 7-OH | 2.9 ± 0.02 | 380 ± 18 | 129 ± 12 | ||
| 8-OH | 3.0 ± 0.07 | 38 ± 8 | 11.7 ± 2.2 | ||
| (S)-W | 4′-OH | 7.1 ± 1.1 | 13.8 ± 2.2 | 2.2 ± 2.0 | |
| 6-OH | 9.9 ± 0.7 | 105 ± 9 | 9.9 ± 1.8 | ||
| 7-OH | 9.9 ± 0.6 | 190 ± 12 | 18.7 ± 3.2 | ||
| CYP2C19 | (R)-AC | 6-OH | 76 ± 10 | 79 ± 12.2 | 1.1 ± 0.6 |
| 7-OH | 72 ± 6.3 | 113 ± 9 | 1.8 ± 0.4 | ||
| 8-OH | 97 ± 14 | 85 ± 9 | 0.7 ± 0.4 | ||
| (R)-W | 6-OH | >200 | 100 ± 16 | <0.5 | |
| 7-OH | >200 | 60 ± 9 | <0.5 | ||
| 8-OH | >200 | 62 ± 10 | <0.5 |
Enzyme kinetics were only established for enzyme-substrate combinations as shown. Other combinations were to low in activity (see Fig. 1). Data are the mean ± S.D. of two separate incubations in triplicate. See Materials and Methods for details.
↵2-a AC, acenocoumarol; W, warfarin.