Table 1.
Kinetic parameters of CYP3A4 reduction by BMR.
| P450(Fe2+)-CO | P450(Fe3+) high-spina | P450(Fe3+) low-spin | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Substrate | k1×103, s−1 | k2×103, s−1 | F1, % | Reducibility, % | k1×103, s−1 | k2×103, s−1 | F1, % | k1×103, s−1 | k2×103, s−1 | F1, % | Reducibility, % |
| No substrate | 22±1 | 0.9±0.2 | 12±7 | 50±9 | 15±9 | 1.2±0.3 | 41±6 | - | 1.0±0.3 | 0 | 42±7 |
| BCT | 13±4 | 3.7±1.0 | 41±20 | 64±7 | 19±8 | 2.8±0.9 | 51±17 | 18±9 | 3.7±0.7 | 66±30 | 48±12 |
| 1-PB | 27±13 | 3.2±0.4 | 25±6 | 39±4 | 19±10 | 2.9±0.4 | 26±3 | 10±6 | 2.6±1.2 | 37±12 | 26±3 |
| TST | 20±7 | 4.0±2.5 | 65±27 | 34±5 | 12±2 | 3.5±1.7 | 74±22 | 12±4 | 2.2±0.8 | 71±22 | 16±4 |
| ANF | 6.9±3.4 | 1.6±0.4 | 36±9 | 78±3 | 9.1±2.8 | 1.5±0.5 | 35±9 | 18±8 | 2.3±0.7 | 11±7 | 75±10 |
*
Represents the relative amplitude of formation of the CO complex of ferrous CYP3A4 (either in P450 or P420 states). The maximal amplitude observed for the P420-CO complex formation was never higher than 13%.
The values given in the table were obtained by averaging the results of 3 – 10 experiments.