Kinetic parameters determined for DHEA 7β- and 16α-hydroxylation by expressed CYP3A forms
Activities determined for DHEA concentrations of 1 to 200 μM were fit to a one-site Michaelis-Menten equation as described under Materials and Methods. Intrinsic clearance is defined as the quotient of Vmax and apparent Km.
Expressed CYP | DHEA Metabolite | Km | Vmax | Clint | |
|---|---|---|---|---|---|
| μM | nmol/min/nmol | ||||
| 3A4 | 7β-OH | 42.3 | 17.9 | 0.423 | |
| 3A7 | 7β-OH | 23.8 | 0.298 | 0.0125 | |
| 3A5 | 7β-OH | 187 | 2.45 | 0.0134 | |
| 3A4 | 16α-OH | 10.0 | 4.33 | 0.433 | |
| 3A7 | 16α-OH | 12.0 | 15.8 | 1.32 | |
| 3A5 | 16α-OH | 218 | 0.391 | 0.0018 | |