TABLE 1.
Methyl parathion and diazinon metabolism by recombinant human P450s
| Cytochrome P450 | Methyl Paraoxon Formation |
PNP Formation |
Diazoxon Formation |
IMP Formation |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Km | Vmax | Clint | Km | Vmax | Clint | Km | Vmax | Clint | Km | Vmax | Clint | |
| μM | nmol · min−1 · nmol P450−1 | ml/(nmol P450 · min) | μM | nmol · min−1 · nmol P450−1 | ml/(nmol P450 · min) | μM | nmol · min−1 · nmol P450−1 | ml/(nmol P450 · min) | μM | nmol · min−1 · nmol P450−1 | ml/(nmol P450 · min) | |
| CYP1A1a | 13.5 ± 14.22 | 1.51 ± 0.40 | 0.11 | |||||||||
| CYP1A2a | 1.96 ± 0.64 | 5.14 ± 0.27 | 2.62 | 16.8 ± 6.07 | 1.38 ± 0.14 | 0.08 | ||||||
| CYP3A4a | 107 ± 29.4 | 9.78 ± 1.52 | 0.09 | 104 ± 39.2 | 5.15 ± 1.09 | 0.05 | ||||||
| CYP2B6b | 1.25 ± 0.32 | 10.39 ± 0.37 | 8.30 | 141 ± 72.3 | 1.42 ± 0.45 | 0.01 | ||||||
| CYP2C19b | 1.03 ± 0.25 | 4.67 ± 0.15 | 4.51 | 48.9 ± 26.6 | 0.62 ± 0.14 | 0.01 | ||||||
| CYP2D6a | 50.3 ± 8.36 | 5.82 ± 0.41 | 0.12 | |||||||||
| CYP2E1c | 54.4 | 2.79 | 0.05 | |||||||||
| CYP1A1b | 3.05 ± 1.08 | 2.35 ± 0.19 | 0.771 | 29.9 ± 30.4 | 1.77 ± 1.00 | 0.059 | ||||||
| CYP1A2b | 23.8 ± 11.1 | 2.66 ± 0.37 | 0.112 | |||||||||
| CYP3A4b | 28.7 ± 27.3 | 5.44 ± 1.43 | 0.19 | 43.7 ± 10.4 | 10.00 ± 0.93 | 0.229 | ||||||
| CYP2B6b | 14.83 ± 7.13 | 5.44 ± 0.58 | 0.366 | 13.94 ± 3.37 | 2.60 ± 0.15 | 0.186 | ||||||
| CYP2C19b | 7.74 ± 11.45 | 4.14 ± 0.84 | 0.535 | 5.04 ± 0.94 | 5.58 ± 0.19 | 1.12 | ||||||
Values represent the mean ± S.E.M. of an = 3 or bn = 4 determinants or cthe mean of n = 2 determinants.