Extraction Partial Purification and Characterization of Polyphenol Oxidase from Tomato

Tomato is one of the most important horticulture crops in India; it is a good sourse of polyphenol oxidase. Polyphenol oxidases play an important role in the resistance of plants to microbial and viral infections and to adverse climatic conditions. Crude polyphenol oxidase was extracted with sodium phosphate buffer from two different varaities of tomatoes and partially purified through ammonium sulphate precipitation and dialysis. The enzyme activity of PPO was determined by spectrophometric assay method using pyrogallol substrate. The specific activity of desi tomato of crude sample was 1.8 U/mg and dialyzed sample was 34 U/mg whereas hybrid tomato (Hybrid 6, 4-4) had the specific activity of 0.81 U/mg in crude sample and 20.09 U/mg in dialyzed sample. Protein concentration of polyphenol oxidase was higher at pH 7 i.e 2.85 µ/mg. The enzyme showed high activity over a broad pH range of 4 - 8. The optimal temperature for enzyme activity was 50-60 °C, respectively. Key words: PPO, sodium phosphate buffer, specific activity, protein concentration, optimum pH.