Table 1

Kinetic constants for glucuronidation of 4-substituted phenols catalysed by UGT1A6

SubstrateControl AdjustedVmaxKmVmax/KmCorrelation Coefficient (R)
nmol/min/mg μM ml/min/mg
4-Methylphenol4.61  ± 0.421800  ± 2302.560.998
4-Ethylphenol2.13  ± 0.10551  ± 543.870.997
4-n Propylphenol0.09  ± 0.01325  ± 580.280.986
4-iso Propylphenol0.28  ± 0.02312  ± 440.890.993
4-tertButylphenol0.20  ± 0.02233  ± 530.590.989
4-Hydroxyacetophenone0.53  ± 0.03833  ± 750.640.998
4-Chlorophenol1.67  ± 0.07246  ± 286.790.995
4-Bromophenol3.00  ± 0.28419  ± 697.160.996
4-Iodophenol2.04  ± 0.11243  ± 288.400.997
4-Nitrophenol1.53  ± 0.2595  ± 1402.570.987

Standard errors in Vmax were in the range of ±4.0 to ±11.4% of the mean with a mean error of ±7.30%. Standard errors in Km were in the range of ±9.0 to ±22.8% of the mean with a mean error of ±14.8%. The mean of control 1-naphthol activities was 1.51 ± 0.21 nmols/min/mg.