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Acetone powder was prepared from raw arrowroots and the polyphenol oxidases of crude enzyme prepared from acetone powder were identified 5 isoenzymes by staining with catechol containing 0.05% phenylene diamine. The crude enzyme was passed through the columns of ion exchangers and gel permeation to fractionate the polyphenol oxidases. The main fraction of polyphenol oxidase appeared to be purified by 94-fold, with the activity yield of 45.4%, and its molecular weight was determined as 38,500 by poly acrylamide gel electrophoresis. The optimal pH and temperature for the enzyme activity were pH 7.5 and 50℃, respectively. The purified enzyme showed a high affinity for catechol and pyrogallol. The Michaelis constant for catechol was calculated to be 16. 67mM according to the Lineweaver-Burk method. The enzyme activity was strongly inhibited by L-ascorbic acid, sodium bisulfite, EDTA and KCN, and totally inhibited, by Fe^(3+) at a concentration of 1mM. However the enzyme was activated by Zn^(2+) approximately 1.7 times at the same concentration.
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