Table 2. Kinetic parameters for quercetin-7-glucuronide by UGT1A9 single expression systems (n = 3).
| 1A9*N-1A9*N | Km(μmol/L) | Vmax (pmol/min/unit) | CLint (μL/min/unit) | % of 1A9*1-HA | % of 1A9*1-CFP |
|---|---|---|---|---|---|
| 9*1-HA | 10.46 ± 1.20 | 864.3 ± 23.7 | 82.6 | 100 | 76.62 |
| 1A9*2-HA | 12.62 ± 1.97 | 257.6 ± 9.5*** | 20.41*** | 24.71 | 18.93 |
| 1A9*3-HA | 42.34 ± 8.23 | 768.2 ± 66.9 | 18.14*** | 21.96 | 16.83 |
| 1A9*5-HA | 12.40 ± 1.43 | 68.02 ± 1.98*** | 5.49*** | 6.65 | 5.09 |
| 1A9*1-CFP | 19.27 ± 2.57 | 2078 ± 68.0 | 107.8 | 130.5 | 100 |
| 1A9*2-CFP | 15.58 ± 1.82 | 263.7 ± 8.304### | 16.92### | 20.48 | 15.70 |
| 1A9*3-CFP | 48.11 ± 6.05 | 600.7 ± 29.6### | 12.49### | 15.12 | 11.59 |
| 1A9*5-CFP | 22.41 ± 1.99 | 408.7 ± 11.0### | 18.24### | 22.08 | 16.92 |
*represents compared with UGT1A9*1-HA, while #represents compared with UGT1A9*1-CFP.Data are the mean ± SD of three independent determinations, and the asterisks indicate differences that are statistically significant (***P < 0.0001, ###P < 0.0001).