TABLE 1

Best-fit-derived kinetic parameters for CP O-glucuronidation by HLM and baculovirus-expressed human UGT isoforms

Each value represents best-fit values ± S.D.

UGT Isoform	1-O-CP Glucuronide Kinetics ± S.D. (n = 3)			3-O-CP Glucuronide Kinetics ± S.D. (n = 3)
UGT Isoform	K_m^c	V_max^c	CL_int^c	K_m or S₅₀^e	V_max	CL_int1 or CL_max^b	K_m	V_max	CL_int2
	μM	pmol/min/mg protein	l/min/mg protein	μM	pmol/min/mg protein	l/min/mg protein	μM	pmol/min/mg protein	l/min/mg protein
Pooled HLM^d	408.2 ± 41.4	16.7 ± 0.6	0.041	46.0 ± 27.0^d	37.9 ± 13.0^d	0.82^d	1027 ± 129.8^d	232 ± 11.2^d	0.226^d
2B7	115.0 ± 14.2	5.4 ± 0.2	0.047	109.1 ± 5.2	46.9 ± 0.4	0.43^a
1A6		<LOQ		1557.0 ± 122.1^e	12.9 ± 0.3^e	0.008^b
1A9		<LOQ		714.4 ± 30.2^e	41.9 ± 0.6^e	0.059^b

<LOQ, below limit of quantitation.
↵a CL_int calculated from Michaelis-Menten kinetics.
↵b CL_max calculated from Hill equation fitted kinetics.
↵c Best-fit kinetic parameters for 1-O-CP glucuronide calculated with substrate inhibition equation K_si (HLM) was 28500 ± 8200 μM and K_si (UGT2B7) was 8090 ± 1240 μM.
↵d Best-fit K_m1 and K_m2 and V_max1 and V_max2 kinetic parameters calculated for 3-O-CP glucuronide with two-enzyme Michaelis-Menten equation.
↵e Best-fit kinetic parameters for 3-O-CP glucuronide calculated using Hill equation.