Table 2. Kinetic parameters of recombinant XDH.

Substrate	XDHwild			XDHcetacean
All assays were performed at 25 °C in 50 mmol/L Potassium phosphate buffer, pH 7.8. Kinetic parameters were determined by monitoring the increase in uric acid at 295 nm.
	Km (mmol/L)	Vmax (μmol/min/mg)		Km (mmol/L)	Vmax (μmol/min/mg)
Xanthine	3.521±0.326	0.0130±0.0004		2.572±0.154	0.0269±0.0005
NAD+	0.420±0.027	0.0262±0.0004		0.195±0.012	0.0315±0.0004