Table 3.
Effect of GSH on substrate binding in CYP3A4*
| Substrate | [GSH], mM | S50. µM | n | ΔFh, %a |
|---|---|---|---|---|
| 1-PB | 0 | 13.0 ±2.6 | 1.51 ±0.09 | 49 ±6 |
| 0.5 | 12.4 ±4.2 (0.839) | 1.44 ±0.14 (0.791) | 50 ±18 (0.872) | |
| 4 | 9.5 ±2.5 (0.204) | 1.22 ±0.20 (0.133) | 53 ±8 (0.865) | |
| 10 | 8.8 ±5.7 (0.183) | 1.06 ±0.19 (0.017) | 75 ±20 (0.137) | |
| ANF | 0 | 3.87 ±0.4 | 2.0 ±0.34 | 39 ±5 |
| 0.5 | 4.54 ±0.1 (0.085) | 1.67 ±0.16 (0.254) | 43 ±1 (0.230) | |
| 4 | 4.51 ±0.9 (0.228) | 1.75 ±0.04 (0.349) | 42 ±2 (0.385) | |
| 10 | 3.59 ±1.9 (0.733) | 1.72 ±0.22 (0.327) | 40 ±3 (0.646) | |
| 7-BFC | 0 | 22.8 ±1.9 | 1.48 ±0.06 | 16 ±3 |
| 0.5 | 14.8 ±6.3 (0.137) | 1.62 ±0.01 (0.041) | 14 ±5 (0.304) | |
| 4 | 27.1 ±4.7 (0.223) | 1.29 ±0.08 (0.063) | 21 ±1 (0.097) | |
| 10 | 19.3 ±7.0 (0.430) | 1.03 ±0.05 (0.007) | 15 ±5 (0.709) | |
| TST-HPCDa | 0 | 108 ±16 | 1.19 ±0.09 | 41 ±9 |
| 0.5 | 125 ±25 (0.216) | 1.14 ±0.10 (0.540) | 33 ±5 (0.300) | |
| 4 | 136 ±14 (0.092) | 1.23 ±0.01 (0.611) | 56 ±11 (0.098) | |
| 10 | 104 ±26 (0.776) | 1.34 ±0.13 (0.114) | 47 ±11 (0.479) | |
*
The values given in the Table were obtained by averaging the result of 2–4 individual measurements and the “±” values show the confidence interval calculated for p = 0.05. The values in parentheses represent the p-values of Student’s T-test for the hypothesis of equality of the respective values with that observed at no GSH added.
a
Maximal amplitude of the substrate-induced spin shift, in percent of the total enzyme content.
b
Water-soluble complex of testosterone with HPCD.