Steroid hydroxylase activities of canine P450s 3A12 and 3A26
| P450 | Androstenedione | Progesterone | Testosterone | |||
|---|---|---|---|---|---|---|
| 6β | 6β | 16α | 6β | 2β | ||
| 3A12 | 3.5, 3.7 | 5.6, 5.9 | 0.81, 0.99 | 4.1, 5.5 | 0.91, 1.5 | |
| 3A26 | 0.47, 0.33 (11) | 0.11, 0.08 (2) | 0.02, 0.02 (2) | 0.45, 0.45 (9) | 0.20, 0.34 (22) | |
Solubilized E. coli membrane preparations containing 10 pmol of 3A26 or 3A12 were reconstituted with 40 pmol cytochrome P450 reductase and 10 pmol cytochrome b5 and analyzed for androstenedione, progesterone and testosterone hydroxylase activity. Substrate concentrations of 250 μM were used throughout. Rates are given in nanomoles of product per minute per nanomole P450 and represent the mean of two to four incubations with two separate preparations of each enzyme. Numbers in parentheses represent 3A26 activity as a percentage of 3A12 activity.