TABLE 2.
Steady-state parameters for glucuronidation of CBN, THC-OH, and THC-COOH by UGT isoforms
Parameters were determined from the fit of initial velocities to a Michaelis-Menten kinetic scheme using GraphPad Prism 4.
| Substrate | UGT Isoforma | Vmax | Km | Vmax/Km |
|---|---|---|---|---|
| nmol/mg protein/min | μM | μl/mg protein/min | ||
| CBN | UGT1A7 | 0.24 ± 0.01 | 19 ± 3.9 | 12.6 |
| UGT1A8 | 0.49 ± 0.03 | 44 ± 8.1 | 11.1 | |
| UGT1A9 | 0.10 ± 0.01 | 3.4 ± 1.3 | 29.4 | |
| UGT1A10 | 0.91 ± 0.05 | 59 ± 10 | 15.4 | |
| THC-OH | UGT1A9 | 0.14 ± 0.01 | 7.3 ± 1.9 | 19.2 |
| UGT1A10 | 0.33 ± 0.03 | 72 ± 19 | 4.58 | |
| THC-COOH | UGT1A1 | 0.22 ± 0.02 | 170 ± 37 | 1.29 |
| UGT1A3 | 0.68 ± 0.06 | 68 ± 17 | 10.0 |
a
All reactions were normalized as described under Materials and Methods.