Regioselectivity of UGT1A3 enzymes to quercetin (n = 3)
Vmax and Vmax/Km are normalized by expression levels of recombinant UGT1A3s. Relative catalytic efficiency of each UGT1A3 enzyme is indicated as percentage of 7-glucuronide.
Monoglucuronide | UGT1A3.1a | UGT1A3.2 | UGT1A3.3 | UGT1A3.4 | UGT1A3.5 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Vmax/Km | Percentage of 7-Glucuronide | Vmax/Km | Percentage of 7-Glucuronide | Vmax/Km | Percentage of 7-Glucuronide | Vmax/Km | Percentage of 7-Glucuronide | Vmax/Km | Percentage of 7-Glucuronide | ||||||
| μl/mg/min | μl/mg/min | μl/mg/min | μl/mg/min | μl/mg/min | |||||||||||
| 7-Glucuronide | 8.310 ± 0.87 | 100 | 2.574 ± 0.17 | 100 | 1.214 ± 0.13 | 100 | 66.60 ± 5.87 | 100 | 20.32 ± 0.42 | 100 | |||||
| 3-Glucuronide | 10.51 ± 0.61 | 126 | 2.073 ± 0.17 | 84 | 1.327 ± 0.05 | 110 | 158.7 ± 10.8 | 238 | 16.26 ± 0.90 | 80 | |||||
| 4′-Glucuronide | 9.216 ± 0.14 | 111 | 0.423 ± 0.04 | 16 | 1.908 ± 0.10 | 158 | 5.866 ± 0.27 | 9 | 1.330 ± 0.02 | 7 | |||||
| 3′-Glucuronide | 22.01 ± 0.90 | 265 | 0.461 ± 0.02 | 18 | 6.929 ± 0.34 | 573 | 1.067 ± 0.10 | 2 | 0.787 ± 0.07 | 4 | |||||
↵ a The data of UGT1A3.1 have been previously reported (Chen et al., 2005a).