Kinetic parameters of berberine demethylenation and 10-demethylation by CYP1A1 and CYP1B1
Kinetic parameters were determined by the nonlinear regression analysis according to each kinetic pattern, as described in Materials and Methods. Data represent the values and the estimated variances (denoted by ±).
| P450 | Type | n | Km (S50), μM | Vmax, nmol/min/nmol P450 | Ki, μM |
|---|---|---|---|---|---|
| CYP1A1 | |||||
| Demethylenation | Positive cooperativity | 4.6 ± 0.2 | 4.87 ± 0.05 | 21.3 ± 0.17 | — |
| 10-Demethylation | Positive cooperativity | 4.1 ± 0.6 | 6.89 ± 0.27 | 6.63 ± 2.46 | — |
| CYP1B1 | |||||
| Demethylenation | Substrate inhibition | — | 0.18 ± 0.07 | 1.03 ± 0.10 | 19.0 ± 7.6 |
| 10-Demethylation | Hyperbolic pattern | 0.8 ± 0.1 | 3.32 ± 0.72 | 0.51 ± 0.04 | — |
—, No available value for this kinetic pattern.