Type I binding interaction with ibuprofen and diclofenac
Type I spectra were acquired using a P450 concentration of 0.2 μM and with ligand concentrations of 2.5 to 1000 μM. Estimates of binding parameters were derived by nonlinear regression analysis of n = 28–56 data points.
CYP2C9 Form | Type I Spectra with Ibuprofen | Type I Spectra with Diclofenac | ||||
|---|---|---|---|---|---|---|
| Δ Absorbancemax | Ks | Δ Absorbancemax | Ks | |||
| μM | μM | |||||
| Wild-type | 0.0123 ± 0.0005 | 170 ± 20 | 0.0093 ± 0.0015 | 11 ± 7 | ||
| K72E | 0.0073 ± 0.0004 | 240 ± 40 | 0.0052 ± 0.0004 | 16 ± 7a | ||
| K72Q | 0.0097 ± 0.0004 | 100 ± 10 | 0.0060 ± 0.0002 | 14 ± 2 | ||
| K72V | 0.0076 ± 0.0004 | 130 ± 20 | 0.0067 ± 0.0003 | 13 ± 3 | ||
| K72L | 0.0061 ± 0.0004 | 50 ± 10 | 0.0042 ± 0.0003 | 24 ± 7 | ||
↵ a Data for the K72E mutant were best fit (P < 0.001) by a model incorporating a second lower affinity binding site, characterized by a first order slope of the binding curve of 2.4 × 10-6 ± 1.0 × 10-6; binding parameters for the high affinity site are shown in the table