Kinetic parameters of the Michaelis-Menten and substrate inhibition kinetics
| Substrate2-a | P4502-b | Product | eq.1 (Hyperbola)2-c | eq. 2(Substrate Inhibition)2-d | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Km | Vmax | α | KS | KI | β | Vmax | RSS | R2 | |||
| Estrone | 1A2 | 2-OH-Estrone | 23.5 ± 0.8 | 10.0 ± 1.6 | No substrate inhibition2-e | ||||||
| Phenacetin | 1A2 | Acetaminophen | 34.5 ± 5.0 | 3.0 ± 0.1 | No substrate inhibition | ||||||
| Ethoxyresorufin | 1A2 | Resorufin | 2.7 ± 0.61 | 414 ± 47 | 8.1 ± 2.3 | 5.3 ± 1.1 | 25.5 ± 8.3 | 0.03 ± 0.01 | 733 ± 58 | 26.8 | 0.988 |
| Diazepam | 2B6 | Nordiazepam | 21.9 ± 7.6 | 2.1 ± 0.2 | No substrate inhibition | ||||||
| Paclitaxel | 2C8 | 6α-OH-Paclitaxel | 7.2 ± 2.3 | 59.2 ± 4.6 | No substrate inhibition | ||||||
| Flurbiprofen | 2C9 | 4′-OH-Flurbiprofen | 12.1 ± 1.2 | 1.5 ± 0.4 | No substrate inhibition | ||||||
| Celecoxib | 2C9 | Hydroxycelecoxib | 3.3 ± 0.3 | 8.9 ± 0.3 | 23.3 ± 4.1 | 5.8 ± 2.3 | 16.4 ± 3.2 | 0.08 ± 0.03 | 10.6 ± 2.4 | 1.26 | 0.991 |
| 2C9*2 | Hydroxycelecoxib | 2.5 ± 0.2 | 4.2 ± 0.1 | 12.2 ± 2.8 | 8.2 ± 3.2 | 10.2 ± 2.8 | 0.11 ± 0.05 | 7.2 ± 1.8 | 0.31 | 0.989 | |
| 2C9*3 | Hydroxycelecoxib | 3.6 ± 0.4 | 0.9 ± 0.0 | 5.1 ± 3.1 | 4.5 ± 1.8 | 24.6 ± 3.8 | 0.05 ± 0.01 | 1.3 ± 0.5 | 0.02 | 0.993 | |
| (S)-Mephenytoin | 2C19 | 4′-OH-Mephenytoin | 18.4 ± 2.0 | 2.5 ± 0.1 | No substrate inhibition | ||||||
| Dextromethorphan | 2D6 | Dextrorphan | 3.1 ± 0.4 | 4.7 ± 0.1 | 23.8 ± 5.6 | 4.8 ± 0.6 | 48.4 ± 6.7 | 0.12 ± 0.06 | 4.3 ± 0.9 | 1.83 | 0.976 |
| Chlorzoxazone | 2E1 | 6-OH-Cholozoxazone | 157 ± 30 | 33.6 ± 2.1 | No substrate inhibition | ||||||
| Testosterone | 3A4 | 6β-OH-Testosterone | 32.0 ± 2.2 | 31.0 ± 0.5 | 5.7 ± 1.2 | 46 ± 21 | 263 ± 34 | 0.61 ± 0.21 | 36 ± 28 | 10.1 | 0.992 |
| Progesterone | 3A4 | 6β-OH-Progesterone | 11.2 ± 1.8 | 30.3 ± 1.6 | 13.2 ± 3.6 | 16.2 ± 4.9 | 96 ± 25 | 0.41 ± 0.14 | 37 ± 11 | 2.69 | 0.996 |
| Benzyloxyresorufin | 3A4 | Resorufin | 3.3 ± 1.1 | 211 ± 19 | 6.3 ± 3.2 | 6.1 ± 2.1 | 39 ± 12 | 0.08 ± 0.02 | 231 ± 59 | 3.1 | 0.981 |
RSS, Residual Sum of Squares.
↵2-a Concentration range of each substrate was shown in Table 1.
↵2-b Baculovirus-expressed individual P450s.
↵2-c Parameters were calculated by the Michaelis-Menten equation (eq. 1) with the data that exclude the inhibited rates for product formation at higher substrate concentrations.
↵2-d Parameters were calculated by the proposed model (eq. 2).
↵2-e No inhibition was observed within the range of substrate concentrations used.