Kinetic parameters of CBZ 10,11-epoxidation by expressed CYP3A4 and CYP3A7
| CYP3A4 | CYP3A7 | ||||||
|---|---|---|---|---|---|---|---|
| Km1 (apparent) | Km2(apparent) | Vmax2 | Vmax2/Km2 | Km(apparent) | Vmax | Vmax/Km | |
| μM | nmol/nmol P450/min | μM | nmol/nmol P450/min | ||||
| CBZ only | 104.8 | 248.3 | 23.64 | 0.0952 | 720.9 | 0.50 | 0.0007 |
| Plus AND | 12.8 | 139.5 | 29.03 | 0.20806 | 382.8 | 0.53 | 0.0014 |
| Plus EST | 2.1 | 666.9 | 24.76 | 0.03713 | 616.7 | 0.15 | 0.0002 |
| Plus DHEA-S | 80.9 | 246.4 | 22.59 | 0.0917 | 280.1 | 0.71 | 0.0025 |
Substrate concentrations were 15 to 500 μM. The reaction was performed in the absence or presence of 100 μM effectors.Km1, Km2, andVmax2 were calculated by a modified two-site equation (Vmax1 = 0) V = (Vmax2S2/Km1Km2)/(1 + S/Km1Km2) (Korzekwa et al., 1998)Km and Vmax were calculated from the Michaelis-Menten equation V =Vmax/(1 + (Km/S)).