TABLE 3.
Enzyme kinetic parameters of exemestane metabolite formation in selected P450s
| P450s | 17-Hydroexemestane |
6-Hydroxymethylexemestane |
||||
|---|---|---|---|---|---|---|
| Km app | Vmax app | Clint app | Km app | Vmax app | Clint app | |
| μM | pmol/mg × min | Vmax/Km | μM | pmol/mg × min | Vmax/Km | |
| CYP3A4 | 98.66 | 0.78 | 0.008 | 93.46 | 78.57 | 0.84 |
| CYP3A5 | 53 | 1.89 | 0.036 | 72 | 9.76 | 0.13 |
| CYP2B6 | 177 | 3.9 | 0.022 | 9 | 1.93 | 0.21 |
| CYP2A6 | 55 | 2.33 | 0.042 | N.D. | N.D. | N.D. |
| CYP1A1 | 28.62 | 4.32 | 0.15 | 104.56 | 0.51 | 0.005 |
| CYP4A11 | 82.7 | 2.57 | 0.031 | N.D. | N.D. | N.D. |
Km app, apparent affinity; Vmax app, apparent maximum reaction velocity; Clint app, apparent intrinsic clearance; N.D., not detected.