TABLE 1

Kinetic parameters of CA-4 glucuronidation in liver microsomes and UGT isoforms

Data are means ± S.E.

Protein Source	K_m	V_max	K_i	S₅₀	Hill Coefficient	Goodness of Fit (R²)
	μM	nmol/min/mg protein	μM	μM	n
HLM^{^a}	33.26 ± 2.90	41.98 ± 1.66	1126 ± 185.5			0.99
UGT1A1^{^b}		2.20 ± 0.31		228.9 ± 88.5	0.78 ± 0.08	0.99
UGT1A3^{^a}	46.48 ± 12.52	1.53 ± 0.23	295.0 ± 94.4			0.92
UGT1A4	N.D.	N.D.	N.D.	N.D.	N.D.	N.D.
UGT1A6^{^b}		3.95 ± 0.13		44.80 ± 3.54	1.61 ± 0.16	0.98
UGT1A9^{^a}	6.98 ± 0.65	12.78 ± 0.29	2271 ± 490.9			0.92
UGT2B4	N.D.	N.D.	N.D.	N.D.	N.D.	N.D.
UGT2B7^{^a}	4.95 ± 0.64	0.236 ± 0.007	6761 ± 4541			0.90
UGT2B15^{^a}	41.74 ± 12.37	0.067 ± 0.009	2182 ± 1900			0.91
UGT2B17^{^a}	47.16 ± 12.34	0.70 ± 0.09	1756 ± 1166			0.93

N.D., not determined because activity below limit of quantification was observed.
↵a Substrate inhibition model (eq. 2).
↵b Sigmoidal kinetic model (Hill equation) (eq. 3).