Table 3 Kinetic parameters of M2 (quercetin-3-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 7.74 ± 0.86   568.0 ± 13.30 37.08 100
1A1*1bCFP/1A9*1HA 10.29 ± 0.98* 256.9 ± 36.17 135.9 ± 5.73*** 13.21*** 35.6
1A9*2HA 3.65 ± 0.40   211.0 ± 3.54 57.89 100
1A1*1bCFP/1A9*2HA 4.02 ± 0.70 117.5 ± 16.94 88.35 ± 5.09* 22.00*** 38.0
1A9*3HA 21.85 ± 4.80 195.7 ± 61.83 467.3 ± 57.26 21.39 100
1A1*1bCFP/1A9*3HA 14.65 ± 2.77 147.0 ± 34.84 664.9 ± 64.76* 45.39** 212.2
1A9*5HA 7.21 ± 1.39   34.75 ± 1.43 4.82 100
1A1*1bCFP1A9*5HA 4.13 ± 1.15* 103.3 ± 23.16 30.73 ± 2.91 7.44** 154.4
  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.