TABLE 3

Kinetic parameters for the interactions between 4MU, 1NP, and AZT glucuronidation by UGT2B7

Kinetic parameters are shown as mean ± S.E. of parameter fit.

Substrate	Modifier	Modifier Effect	V_max	K_s	K_i	α	δ^a
			pmol/min · mg	μM
4MU	AZT	Inhibition^b	921 ± 25	2895 ± 200	176 ± 17	0.01 ± 0.004^c
	1NP	Inhibition^d	1140 ± 60	1872 ± 215	80 ± 2.8	0.10 ± 0.04^c
1NP	AZT	Inhibition^b	495 ± 6.8	1631 ± 164	379 ± 46	0.01 ± 0.002^c
	4MU	Activation^e	480 ± 10	485 ± 78		0.10 ± 0.03^c
AZT	4MU	Inhibition^f	37 ± 0.5	351 ± 15	369 ± 30	0.10 ± 0.02^g	0.31 ± 0.04
	1NP	Inhibition^f	38 ± 0.8	343 ± 23	145 ± 16	0.08 ± 0.02^g	0.39 ± 0.08

↵ a From eq. 4.
↵ b Three-site kinetic model as described by eq. 5, with β = 2.
↵ c Cooperative binding of substrate.
↵ d Three-site kinetic model as described by eq. 6, with β = 2.
↵ e Three-site kinetic model as described by eq. 7, with β = 2 (K_a = 432 ± 196 μM).
↵ f Generic two-site kinetic model as described in eq. 4, with β = 2 and γ = 1.
↵ g Cooperative binding of modifier.