Isolation, Fractionation, and Characterization of Xanthine Oxidase from Goat’s Milk

Xanthine oxidase (XO) is an oxidoreductase enzyme that catalyzes hypoxanthine's hydroxylation to xanthine and then to uric acid. This study aims to isolate and characterize the xanthine oxidase enzyme from goat's milk. Xanthine oxidase enzyme was isolated from fresh goat's milk with the addition of NaCl and centrifuged to obtain a crude extract of the enzyme, which was then fractionated using ammonium sulfate. Characterization was carried out to determine the optimum condition of the enzyme, namely the determination of optimum time and pH. The results showed that the crude extract of the enzyme had a specific activity of 0.0019 mU/mg. The highest specific activity of 0.0327 mU/mg was found at a 20-40% ammonium sulfate saturation level. The dialyzed enzyme had a specific activity of 0.0402 mU/mg. The optimum activity was found at pH 6 and an incubation time of 25 minutes. It is concluded that goat's milk can be used as a source of xanthine oxidase enzyme in pursuing gout drug agents.