Table 1

Kinetic parameters for SN-38 glucuronidation by WT and variant (G71R, P229Q, and Y486D) human UGT1A1s^1-a

UGT1A1	ApparentK_m	V_max	V_max/K_m	NormalizedV_max^1-b	NormalizedV_max/K_m^1-b
	μM	pmol/min/mg protein	μl/min/mg protein	pmol/min/mg protein	μl/min/mg protein
WT	11.5 ± 0.7	16.4 ± 4.0	1.40 ± 0.26	16.4 ± 4.0	1.40 ± 0.26
G71R	14.0 ± 0.4	3.7 ± 1.0^1-160	0.26 ± 0.07^1-160	9.2 ± 2.4^1-150	0.66 ± 0.17^1-160
P229Q	18.0 ± 1.2	15.4 ± 3.2	0.86 ± 0.21^1-150	12.9 ± 2.7	0.73 ± 0.18^1-160
Y486D	63.5 ± 7.8^1-160	1.9 ± 0.5^1-160	0.03 ± 0.01^1-160	4.2 ± 1.0^1-160	0.07 ± 0.02^1-160

↵1-a The results were expressed as the mean ± S.E.M. from three-independent transfection experiments. Asterisks signify data significantly different from that of WT at the following levels:
↵1-150 p < 0.05;
↵1-160 p < 0.01.
↵1-b V_max values were normalized by the relative protein expression level, where the ratios for G71R, P229Q, and Y486D were 0.40, 1.2, and 0.45, respectively.