. 2010 Jul 8;285(36):28044–28053. doi: 10.1074/jbc.M110.128561

TABLE 2.

Kinetic parameters for the steady-state and reductive half-reactions of xanthine oxidase

–, Steady-state reactions not performed in the present work. 6,8-DHP, 6,8-dihydroxypurine.

Substrate	pH 8.5						pH 7.0
Substrate	k_cat	K_m	k_cat/K_m	k_red	K_d	k_red/K_d	k_cat	K_m	k_cat/K_m
	s⁻¹	μm	μm⁻¹s⁻¹	s⁻¹	μm	μm⁻¹s⁻¹	s⁻¹	μm	μm⁻¹s⁻¹
Xanthine	15/12^a/15^b/16^c	8.0/6^a/11^b/15^c	1.9/1.9^a/1.1^c	21/17^a/13^b	15/17^a	1.4/1.0^a	7.3^a/3.1^c	0.56^a/0.26^c	13^a/12^c
Hypoxanthine	16/15^c	4.6/13^c	3.5/1.2^c	21	4.6	4.6	10	7.5	1.3/0.083^d
6,8-DHP	7.1	4.9	1.4	10	10	1.0	–	–	–

^a From Ref. 29.

^b From Ref. 30.

^c From the hyperbolic fit of the data from spectral deconvolution of exhaustive turnover reactions of xanthine oxidase with hypoxanthine in the present work. Kinetics of hypoxanthine is followed by its consumption, and kinetics of xanthine is followed by production of uric acid.

^d From the linear fit of the data from spectral deconvolution of exhaustive turnover reactions in the present work.