Table 2.
Kinetic parameters of BFT 5β-hydroxylation in HLM, recombinant human CYP3A4 and CYP3A5.
| Enzyme Source | High-affinity site |
Low-affinity site |
||
|---|---|---|---|---|
| Vmax | Km | Vmax | Km | |
| HLM | 33.31 ± 12.64 | 3.71 ± 2.68 | 107.30 ± 11.77 | 133.70 ± 72.23 |
| CYP3A4 | 6.87 ± 3.59 | 3.46 ± 3.51 | 33.70 ± 3.08 | 122.40 ± 56.5 |
| Vmax | Km | Ksi | CLint | |
| CYP3A5 | 3.45 ± 0.09 | 2.91 ± 0.24 | 170.00 ± 12.69 | 1186.12 |
Km values are μM, Vmax values are nmol ⋅ min−1 ⋅ mg−1 for liver microsomes or nmol ⋅ min−1 ⋅ nmol−1 of P450 for CYP3A. The range of substrate concentrations was 1–250 μM. Each value was the mean ± S.D. of three determinations performed in duplicate.