Table 1.
Parameters of the interaction of CYP3A4 and its derivatives with substrates
| Protein | Parameter | Substrate | ||
|---|---|---|---|---|
| BCT | 1-PB | ANF | ||
| CYP3A4 | S50 or KD, µM | 0.65 ± 0.33 | 13.2 ± 2.9 | 4.8 ± 2.2 |
| n | n/a | 1.6 ± 0.20 | 1.9 ± 0.3 | |
| ΔFh(%)a | 40 ± 15 | 40 ± 8 | 36 ± 8 | |
| CYP3A4-BADAN | S50 or KD, µM | 0.68 ± 0.48 | 8.0 ± 0.3 | 4.7 ± 0.9 |
| n | n/a | 1.4 ± 0.3 | 1.5 ± 0.5 | |
| ΔFh(%)a | 30 ± 8 | 42 ± 7 | 30 ± 6 | |
| CYP3A4(C58,C64) | S50 or KD, µM | 0.71 ± 0.34 | 8.7 ± 2.7 | 2.7 ± 0.5 |
| n | n/a | 1.6 ± 0.2 | 2 ± 0.1 | |
| ΔFh(%)a | 39 ± 7 | 36 ± 7 | 32 ± 9 | |
| CYP3A4(C58,C64)-BADAN | S50 or KD, µM | 0.62 ± 0.13 | 7.5 ± 1.6 | 2.2 ± 0.3 |
| n | n/a | 1.7 ± 0.6 | 1.5 ± 0.2 | |
| ΔFh(%) | 40 ± 8 | 31 ± 2 | 28 ± 4 | |
a
The amplitude of the substrate-induced changes in the high-spin content. In the absence of substrate the content of the high-spin state was within the range of 12–18% for all enzyme variants.
The values shown in the table are determined from the fitting of the titration curves to the Hill equation (for 1-PB and ANF) or to the equation for the isotherm of bimolecular association (for BCT). The results represent the averages of two to four individual measurements. The deviations correspond to the confidence intervals calculated for p = 0.05.