Table 2.
NADPH oxidation and H2O2 product formation by CYP3A4 and its mutants.
| nmol/min/nmol of P450 |
||||||
|---|---|---|---|---|---|---|
| CYP3A4 | MDZ | NADPH oxidation | 1′-OH MDZ formation | 4-OH MDZ formation | H2O2 formation | H2O formation a |
| wild type | + | 51.6±2.8 | 7.7±0.6 | 3.8±0.4 | 8.6±0.4 | 15.8 |
| - | 49.7±2.0 | 8.0±0.1 | 20.9 | |||
| C98A | + | 61.7±4.8 | 8.2±0.6 | 4.9±0.3 | 9.7±0.7 | 19.5 |
| - | 50.6±3.4 | 8.4±0.5 | 21.1 | |||
| C98S | + | 55.2±3.1 | 8.3±0.4 | 4.5±0.2 | 8.9±0.7 | 16.8 |
| - | 51.6±2.7 | 7.9±0.2 | 21.9 | |||
| C98F | + | 43.6±3.2 | 5.5±0.4 | 1.3±0.1 | 10.6±0.9 | 13.1 |
| - | 37.7±3.0 | 7.8±0.6 | 15.0 | |||
| C98W | + | 30.2±1.1 | 1.1±0.2 | 0.4±0.1 | 13.8±1.4 | 7.5 |
| - | 26.1±0.2 | 5.8±0.5 | 10.2 | |||
a
H2O formation was determined by calculating the difference between total NADPH consumption and the sum of H2O2 and hydroxylated products formed. The result was divided by 2 because four electrons would be required to reduce O2 to H2O. No correction was made for O2-, which was not measured. Values represent the means ± SD of three determinations.