Abstract: Crude lipoxygenase (LOX) from Cherry-valley duck breast muscle was purified through 20%－40% ammonium sulfate fractionation and DEAE-Sepharose column chromatography. LOX was separated by gradient elution of DEAESepharose column with 0.3－0.35 mmol/L NaCl solution, resulting in a purification factor of 54.3. The molecular weight of the purified LOX was measured by SDS-PAGE to be 96 kD. Slight differences in enzymatic properties between the crude LOX and the purified LOX were observed. Using linoleic acid as the substrate, the optimal substrate concentrations, reaction temperatures and pH values were 6.4 mmol/L and 10 mmol/L, 40 ℃ and 30 ℃, and 5.0 and 5.5, respectively, and the Michaelis constant (Km) and maximum velocity (Vmax) for the purified LOX were 1.139 mmol/L and 0.07608 U/min, respectively. The purified LOX had a higher affinity for the substrate than the crude LOX.

Key words: Cherry-valley duck, lipoxygenase (LOX), isolation and purification, enzymatic characteristics