Table 2 Kinetic parameters of M1 (quercetin-7-glucuronide) formation by single expressed UGT1A9*NHA and double expressed UGT1A1*1bCFP/1A9*NHA systems.

From: Inter-isoform Hetero-dimerization of Human UDP-Glucuronosyltransferases (UGTs) 1A1, 1A9 and 2B7 and Impacts on Glucuronidation Activity

1A9*N or 1A1*1b/1A9*N Km (μM) Ksi (μM) Vmax (pmol/min/unit) CLint (μL/min/unit) % of 1A9*NHA
1A9*1HA 9.10 ± 0.21 1.56 ± 0.06 791.3 ± 4.160 45.30 100
1A1*1bCFP/1A9*1HA 14.87 ± 0.43*** 1.93 ± 0.08 90.55 ± 0.47*** 3.05*** 6.7
1A9*2HA 12.62 ± 1.97   257.6 ± 9.50 20.41 100
1A1*1bCFP/1A9*2HA 11.11 ± 1.84   45.93 ± 1.85*** 4.13*** 20.2
1A9*3HA 42.34 ± 8.23   768.2 ± 55.91 18.14 100
1A1*1bCFP/1A9*3HA 41.36 ± 7.71   328.8 ± 22.25** 7.95** 43.8
1A9*5HA 12.40 ± 1.43   68.02 ± 1.98 5.48 100
1A1*1bCFP/1A9*5HA 7.39 ± 1.16*   16.87 ± 0.57*** 2.28*** 41.6
  1. Asterisks indicate statistically significant differences compared with UGT1A9*NHA single expression systems (***P < 0.0001, **P < 0.005, *P < 0.05). Data are mean ± SD of three independent determinations.