Table 5.
Enzyme kinetic parameters for the formation of picroside II sulfate (M8) from picroside II (M4) in human liver S9 fractions and human cDNA-expressed SULT enzymes.
| Enzymes | Km (μM) | Vmax | Ki (μM) | Clint |
|---|---|---|---|---|
| Human liver S9 | 45.1 (22.0) | 472.2 (101.9) | 799.8 (417.1) | 10.5 |
| SULT1A1*1 | 9.0 (2.6) | 10,100 (921) | 844.4 (263.0) | 1122 |
| SULT1A1*2 | 10.8 (3.8) | 13,490 (1710) | 468.9 (163.9) | 1249 |
| SULT1A2 | 54.0 (13.4) | 6134.5 (688.0) | 2859.3 (1854.2) | 113.6 |
| SULT1A3 | 1271.7 (423.6) | 82,370 (21746) | 1265.9 (551.3) | 64.8 |
| SULT1C4 | 553.1 (33.4) | 61,140 (2036) | - | 110.5 |
| SULT1E1 | 12.9 (3.4) | 36,250 (3274) | 995.3 (356.9) | 2810 |
Vmax: pmol/min/mg protein; Clint: μL/min/mg protein. Standard errors are presented in parentheses. The amounts of picroside II sulfate was determined using the calibration curve for picroside II.