Purificiation and Some Properties of Polyphenol Oxidase from Van Apple (Golden Delicious)

Abstract

Polyphenol oxidase was isolated from van apple, with a 4.0-fold purification of polyphenol oxidase by ammonium sulfate and DEAE cellulose being achieved. The optimum pH was 4 and for this enzyme, the optimum temperature was 50°C. V_max and K_m values were found of Lineweaver-Burk graphs. Potassium cyanide, benzoic acid, citric acid, MnCl₂, NaCl, NaNO₂ and CuSO₄ were used as inhibitors. The enzyme activity was inhibited by benzoic acid, CuSO₄ and NaCl, polyphenol oxidase activity at 10 mM, whereas NaNO₂, citric acid, KCN and MnCl₂ enhanced by polyphenol oxidase activity at 10 mM.