Table 3.
Enzyme | kcat (mol substrate oxidized/mol P450/min)a
|
||||
---|---|---|---|---|---|
MOCb,c | MMCb,c | MBCb,c | MFCb,c | EFCc,d | |
CYP1C1 | 0.70, 0.85 | 1.35, 1.11 | 0.215, 0.27 | 0.36, 0.43 | 1.51 ± 0.14 |
CYP1C2 | 0.29, 0.36 | 0.18, 0.22 | 0.04, 0.06 | 0.04, 0.04 | 1.18 ± 0.02 |
CYP1D1e | 0 | 0 | 0 | 0 | 0 |
kcat values obtained with microsomal preparations from yeast expressing the indicated CYP via pYeDP60, and in which P450 content could be measured. The P450 contents in these preparations were 0.12 and 0.04 nmol/mg for CYP1C1 and CYPC2, respectively. The final concentration of methanol (with all coumarins except MBC) or DMF (MBC assays) was 0.2%.
Abbreviations are: 7-methoxy-coumarin (MOC); 7-methoxy-4-methyl-coumarin (MMC); 7-methoxy-4-bromomethyl-coumarin (MBC); 7-methoxy-4-trifluoromethyl-coumarin (MFC); and 7-ethoxy-4-trifluoromethyl-coumarin (EFC).
These values were obtained from measurements with two independent preparations, and both values are shown.
These values are from measurements with four to eight independent preparations.
No dealkylation activity was detected with CYP1D1 for any of these substrates.