Table 2

Kinetic constants for glucuronidation of 4-substituted phenols catalysed by UGT1A9

nmol/min/mg μM ml/min/mg
4-Methylphenol0.47  ± 0.02675  ± 136.200.965
4-Ethylphenol0.38  ± 0.01634  ± 611.240.981
4-n Propylphenol0.56  ± 0.03653  ± 1310.530.973
4-iso Propylphenol0.78  ± 0.08751  ± 1515.290.973
4-nButylphenol0.57  ± 0.036154  ± 383.690.991
4-sec Butylphenol0.91  ± 0.03999  ± 139.200.993
4-tert Butylphenol1.26  ± 0.1275  ± 1616.800.989
4-Cyclopentylphenol1.02  ± 0.03160  ± 136.380.997
4-Phenylphenol0.36  ± 0.0367  ± 215.430.945
Methyl 4-hydroxybenzoate1.11  ± 0.0582  ± 1113.540.993
Ethyl 4-hydroxybenzoate0.96  ± 0.0594  ± 1610.230.988
Propyl 4-hydroxybenzoate0.90  ± 0.04120  ± 167.530.993
Butyl 4-hydroxybenzoate0.91  ± 0.03113  ± 128.030.993
4-Hydroxybenzophenone0.97  ± 0.0657  ± 1217.020.983
4-Hydroxyacetophenone1.07  ± 0.05298  ± 363.590.994
4-Fluorophenol0.81  ± 0.03213  ± 513.780.993
4-Chlorophenol1.02  ± 0.0743  ± 923.720.986
4-Bromophenol0.94  ± 0.0941  ± 1122.900.974
4-Iodophenol0.78  ± 0.0521  ± 637.100.962
4-Phenylazophenol0.28  ± 0.0179  ± 153.540.989
4-Nitrophenol0.93  ± 0.0788  ± 1910.580.979
4-Methoxyphenol0.90  ± 0.06236  ± 353.800.994
4-Ethoxyphenol1.12  ± 0.08271  ± 384.130.995
4-Propoxyphenol0.53  ± 0.05211  ± 492.530.984

Standard errors in Vmax were in the range of ±2.5 to ±11.1% of the mean with a mean error of ±6.3%. Standard errors in Km were in the range of ±7.8 to ±31.8% of the mean with a mean error of ±19.4%. The mean of control propofol activities was 0.465 ± 0.12 nmols/min/mg.