P450s | Metabolite Formation Rate | ||
---|---|---|---|
24R,25(OH)2D3 | 4β,25(OH)2D3 | 4α,25(OH)2D3 | |
pmol · min−1 · pmol−1 | |||
CYP3A4 (b5 coexpressed) | BLQ | 2.27 ± 0.22 | 1.26 ± 0.27 |
CYP3A5 (b5 coexpressed) | BLQ | 0.24 ± 0.03 | 0.17 ± 0.02 |
CYP24A1a | 2.39 ± 0.63 | N.D. | N.D. |
Other P450sb | N.D. | N.D. | N.D. |
BLQ, below limit of quantification; N.D., not detected.
↵a Metabolism of 25OHD3 by CYP24A1 was conducted in Dr. T. Sakaki's laboratory (Toyama Prefectural University). Incubation conditions: CYP24A1 (20 nM), adrenodoxin (200 nM), adrenodoxin reductase (20 nM), 1 mM NADPH, and 12.5 μM 25OHD3 in 100 mM Tris-HCl (pH 7.4, 1 mM EDTA) at 37°C for 10 min. After incubation, the products were extracted and shipped to the University of Washington. LC-MS/MS analysis was performed as described under Materials and Methods.
↵b Other P450s: CYP1A1, -1A2, -2A6, -2B6, -2C8, -2C9, -2C19, -2D6, -2E1, -2J2, and -3A7.