Table 1

Catalytic activities of E. coli membranes containing co-expressed P450 2C19 and human microsomal NADPH-P450 reductase in comparison with a reconstituted system

P450 2C19 Co-expressed with ReductaseP450 2C19 Reconstituted with Reductase
min−1 min−1
(S)-Mephenytoin
 4′-hydroxylation5.54.3
Diazepam
N-Demethylation1.71.6
(R)-Warfarin
 4′-Hydroxylation 0.07 0.10
 6-Hydroxylation 0.12 0.18
 7-Hydroxylation 0.21 0.34
 8-Hydroxylation 0.25 0.31
  • Turnover numbers for the three CYP2C19 substrates (S)-mephenytoin (400 μM), diazepam (100 μM), and (R)-warfarin (500 μM) are given in nmol product formed/min/nmol P450 and represent the mean of duplicate determinations that differed <20%.