TABLE 1

Derived morphine glycosidation kinetic constants generated in the absence and presence of BSA (2% w/v) with morphine as the variable substrate

Data are shown as the mean ± S.D. for HLM from five separate livers.

Pathway	Cofactor	Without BSA				With BSA
Pathway	Cofactor	K_m or S₅₀	V_max	CL_int	n	K_m or S₅₀	V_max	CL_int	n
		mM	pmol/min/mg	µl/min/mg		mM	pmol/min/mg	µl/min/mg
Morphine 3-glucoside	UDP-Glc	5.56 ± 1.03	1581 ± 631	0.30 ± 0.14	—	0.63 ± 0.12^{^b}	1536 ± 560	2.54 ± 1.29^{^b}	—
	1:1^{^e}	3.82 ± 0.26^{^c}	260 ± 25^{^d}	0.07 ± 0.01^{^d}	—	0.89 ± 0.14^{^b}^,^{^c}	265 ± 18^{^d}	0.30 ± 0.03^{^b}^,^{^d}	0.77 ± 0.01
M3G	UDP-GlcUA	3.63 ± 1.11	2803 ± 599	0.82 ± 0.24	0.86 ± 0.03	0.45 ± 0.09^{^b}	2429 ± 588^{^a}	5.74 ± 2.32^{^b}	0.83 ± 0.04
	1:1	5.07 ± 0.29^{^c}	2747 ± 163	0.54 ± 0.02^{^c}	0.93 ± 0.02	0.61 ± 0.09^{^b}^,^{^c}	2500 ± 134	4.14 ± 0.35^{^b}	0.89 ± 0.03
M6G^{^f}	UDP-GlcUA	2.88 ± 1.21	387 ± 79	0.15 ± 0.05	0.89 ± 0.03	0.36 ± 0.07^{^b}	353 ± 96	1.03 ± 0.41^{^b}	—
	1:1	4.72 ± 0.43^{^c}	460 ± 40	0.10 ± 0.02^{^c}	—	0.51 ± 0.08^{^b}^,^{^c}	396 ± 20	0.78 ± 0.08^{^b}	—

↵^a P < 0.05; comparisons for each glycoside ± BSA for single cofactor experiments.
↵^b P < 0.01; comparisons for each glycoside ± BSA for single cofactor experiments.
↵^c P < 0.05; comparisons for each glycoside between single and mixed cofactor experiments.
↵^d P < 0.01; comparisons for each glycoside between single and mixed cofactor experiments.
↵^e 1:1; combination of 5 mM UDP-Glc and 5 mM UDP-GlcUA.
↵^f K_si for M6G formation in presence of BSA = 62 ± 6 mM.