Purification and characterization of polyphenol oxidase from hemşin apple (Malus communis L.)

Abstract

The polyphenol oxidase (PPO) enzyme was purified and characterized from Hemşin Apple (Malus communis L.), which was organically grown in Hemşin, in the Rize province of Turkey. Enzyme (PPO) activation was determined with catechol substrate. Apples were homogenized with homogenate buffer (pH 8.5). This process was followed by precipitation with (20-80%) saturated solid (NH4)2SO4 and dialysis. Finally, purification with DE52-Cellulose ion-exchange and Sephadex G-25 columns was performed. Experiments were performed at an optimum pH (5.5) and optimum temperature (30-40°C). The kinetic and thermal parameters Km (3.40 mM), Vmax (333.3 EU/mL.min), Ea (3.57 kcal), H (2.968 kcal/mol), Q10 (1.33), kcat (24.57 min-1) and V0 (7.2x103 mM-1.min-1) were assessed. Additionally, the effects of Mg2+, Pb 2+, Fe2+, Fe3+, Cd2+, Cu2+, Zn2+, Co2+, Al3+, Mn2+ and Na+ on enzyme activity was recorded, and the IC50 values, K̄ values and inhibition types were determined.