Table 5 Kinetic parameters of M2 (quercetin-3-glucuronide) formation by single expressed UGT1A9*NCFP and double expressed UGT1A9*NCFP/2B7*NHA systems.

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

1A9*NCFP or 1A9*N/2B7*N Km (μM) Ksi (μM) Vmax (pmol/min/unit) CLint (μL/min/unit) % of 1A9*NCFP
1A9*1CFP 7.79 ± 0.34   1575 ± 8.08 109.7 100
1A9*1CFP/2B7*1HA 7.78 ± 1.09   5102 ± 203.1*** 357.0*** 325.4
1A9*1CFP/2B7*71SHA 8.16 ± 1.48*   2861 ± 158.9*** 196.7*** 179.3
1A9*1CFP/2B7*2HA 8.22 ± 0.59   4175 ± 67.87*** 274.3*** 250.1
1A9*1CFP/2B7*5HA 2.57 ± 0.25   2694 ± 33.12*** 1049*** 956.8
1A9*2CFP 21.02 ± 6.99 233.0 ± 120.4 175.5 ± 31.82 8.35 100
1A9*2CFP/2B7*1HA 8.17 ± 0.65*   194.7 ± 4.05 12.33* 147.6
1A9*2CFP/2B7*71SHA 6.81 ± 1.16*   372.0 ± 24.75** 29.59*** 354.5
1A9*2CFP/2B7*2HA 7.29 ± 1.59* 251.2 ± 74.53 300.3 ± 25.82* 41.22*** 493.7
1A9*2CFP/2B7*5HA 12.75 ± 2.21 209.2 ± 50.92 151.1 ± 12.60 11.85* 141.9
1A9*3CFP 34.39 ± 7.55 139.5 ± 40.24 688.3 ± 96.12 20.01 100
1A9*3CFP/2B7*1HA 77.71 ± 34.34 105.2 ± 59.67 1572 ± 524.9* 20.23 101.0
1A9*3CFP/2B7*71SHA 39.23 ± 11.71 85.86 ± 29.50 788.0 ± 159.7 20.09 100.4
1A9*3CFP/2B7*2HA 7.66 ± 1.60   485.4 ± 22.87* 63.37** 316.6
1A9*3CFP/2B7*5HA 6.14 ± 0.52**   378.1 ± 5.00* 30.94** 154.6
1A9*5CFP 34.65 ± 9.19 211.5 ± 87.71 448.7 ± 73.77 12.95 100
1A9*5CFP/2B7*1HA 7.13 ± 0.41   137.9 ± 0.98** 9.83*** 75.9
1A9*5CFP/2B7*71SHA 6.50 ± 0.42*   464.5 ± 3.40 35.97*** 277.8
1A9*5CFP/2B7*2HA 14.17 ± 3.00* 286.4 ± 99.91 415.5 ± 42.54** 29.32** 226.4
1A9*5CFP/2B7*5HA 9.56 ± 2.79*   308.8 ± 36.08* 20.81* 160.7
  1. Asterisks indicate statistically significant differences compared with UGT1A9*NCFP single expression systems (***P < 0.0001, **P < 0.005, *P < 0.05). Data are mean ± SD of three independent determinations.