Table 3.

Kinetic parameters for the reaction of XOR from bovine milk

Enzyme	Substrate	Electron acceptor	Detection wavelength	Km (μM)	kcat (s−1)	kcat/Km (s−1/μM)
XO	Xanthine	O2	295 nm	11.51 ± 1.18	14.06 ± 0.41	1.22
XDH	Xanthine	NAD+	340 nm	5.29 ± 0.48	11.08 ± 0.38	2.10
XDH	Hypoxanthine	NAD+	340 nm	2.64 ± 0.29	6.37 ± 0.28	2.42
XDH	Allopurinol	NAD+	340 nm	4.23 ± 0.52	1.83 ± 0.92	0.43
XOR	Xanthine	PMS	550 nm	24.02 ± 2.49	40.78 ± 1.33	1.70
XOR	Hypoxanthine	PMS	550 nm	5.29 ± 0.24	34.20 ± 0.39	6.47
XOR	Allopurinol	PMS	550 nm	3.59 ± 0.45	26.17 ± 1.96	7.30

Values reported are the mean ± S.E.