Characterization of Polyphenol Oxidase and Peroxida se From Iranian Medlar ( Mespilus germanica L.) Fruit

Abstract

In this study, the crude protein extract containing PolyPhenolOxidase (PPO) and Peroxidases (POD) were extracted from medlar fruit ( Mespilus germanica L.) grown in Golestan Province, Iran. POD and PPO activities wer e studied using guaiacol and catechol as substrates, respectively. The effect of pH, temperature and thermal stability, inhibitors and cations were investigated. Results s howed that V max was higher for PPO compared to the POD. The optimum pHs for POD and PP O were obtained at 6.5 and 5.5, respectively. The optimum temperature for both enzy mes was 35°C. The Iranian medlar POD was more thermal stable than the PPO. Ascorbic acid had the highest inhibitory effect on both enzymes. Ca 2+ and Zn 2+ had the highest decreasing and increasing effect o n both enzymes. Keywords: Characterization, Medlar, Peroxidase, Polyphenolox idase.