The marker substrate reaction from HLMs and cDNA-expressed P450
Enzyme Activity | |||||
|---|---|---|---|---|---|
| Enzyme | Marker Substrate Reaction | HLMs | cDNA-Expressed P450 | Amount of cDNA-Expressed P450 per Incubationa | |
| pmol/pmol total P450/min | pmol/pmol P450/min | pmol | |||
| CYP2A6 | Coumarin 7-hydroxylation | 2.47 | 7.2 | 14.0 | |
| CYP2C8 | Paclitaxel 6α-hydroxylation | 0.56 | 7.6 | 2.8 | |
| CYP2C9 | Diclofenac 4′-hydroxylation | 4.12 | 22.0 | 7.6 | |
| CYP2C19 | S-mephenytoin 4′-hydroxylation | 0.24 | 25.0 | 0.4 | |
| CYP3A4 | Testosterone 6β-hydroxylation | 8.87 | 170.0 | 2.0 | |
| CYP3A5 | Testosterone 6β-hydroxylation | 8.87 | 14.0 | 25.0 | |
↵ a The amount of cDNA-expressed P450 used per incubation had P450 isozyme activity approximately equivalent to that used in HLM incubations, which contained 40 pmol of P450 and 0.1 mg of microsomal proteins.