Table 1.
Secosteroid | 1α-hydroxylase activity (mol product/min/mol CYP27B1) |
---|---|
20S(OH)D3 | 0.135 ± 0.005 |
20S,23R(OH)2D3 | 0.117 ± 0.027 |
20S,23S(OH)2D3 | 0.258 ± 0.020 |
20S,25(OH)2D3 | 7.98 ± 0.24 |
Secosteroids were incorporated into phospholipid vesicles at a ratio of 0.025 mol secosteroid/mol phospholipid and incubated with mouse CYP27B1 (0.2 μM) for 20 min for all substrates except 20S,25(OH)2D3 which was incubated for 5 min. Extracted samples were analyzed by reverse-phase HPLC. Data are mean ± SD, n=3.