Strawberry Polyphenoloxidase: Purification and Characterization

ABSTRACT Stable and highly active polyphenoloxidase (PPO) extracts were obtained using polyvinylpyrrolidone, Amberlite XAD‐4, Triton X‐100, and protease inhibitor in pH 5.25 buffer. Citrate and phosphate prevented binding of PPO to pectin. Phenyl sepharose chromatography resolved PPO into two isozymes (PPO‐F1 and PPO‐F2) both separated from pectin. PPO‐F1 had a molecular weight of 111,000, did not penetrate the running gel during electrophoresis, and was bound by concanavalin suggesting that it contained carbohydrate. PPO‐F2 resolved into two peaks during DEAE‐chromatography, had a molecular weight of 34,500, and resolved into two bands during electrophoresis.