Kinetic parameters for testosterone 6β-hydroxylation and erythromycin N-demethylation in microsomal preparations
| Microsome | Testosterone 6β-Hydroxylation | ErythromycinN-Demethylation | ||
|---|---|---|---|---|
| Km (μM) | Vm (nmol/min/mg) | Km (μM) | Vm (nmol/min/mg) | |
| HL 3926 | 128 ± 12 | 20 ± 0.8 | 78 ± 9 | 2 ± 0.09 |
| HL 24493 | 53 ± 6 | 3 ± 0.1 | 44 ± 7 | 0.41 ± 0.02 |
| CYP3A4/OR | 66 ± 8 | 2 ± 0.1 | 46 ± 5 | 0.22 ± 0.01 |
Incubations were performed with human liver microsomes (HL 3926, HL 24493) or microsomes from cells containing human CYP3A4 and P450 reductase (CYP3A4/OR) at 37° C as described in Materials and Methods. Errors represent the SE values of the parameters.