文章基本信息

标题：Characterization of Polyphenol Oxidase From White Cherry Fruit (Starks Gold)
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作者：M. Ümit Ünal ; Özge Gökkaya ; Aysun Şener 等
期刊名称：Gida : Journal of Food
印刷版ISSN：1300-3070
电子版ISSN：1309-6273
出版年度：2011
卷号：36
期号：5
出版社：Association of Food Technology, Turkey
摘要：Polyphenol oxidase (PPO) from white cherry fruit (Starks Gold) was extracted and purified through (NH₄)₂SO₄ precipitation, dialysis and ion exchange chromatography. The enzyme showed two peaks with PPO activity on toyopearl 650 m column, which were denoted as isoenzyme a and isoenzyme b. A 3.9 fold purification of isoenzyme a with a recovery of 34.9 % and 76.7 fold purification of isoenzyme b with a recovery of 54.3 % were achieved. Ph optima of isoenzyme a and b were 4.5 and 4.98, respectively. The temperature optima for enzyme activity were found to be 20°C for isoenzyme a and 30°C for isoenzyme b. The affinity of isoenzyme b for catechol as substrate was higher than that of isoenzyme a. Activation energies and z values were found to be 22.1°C (r²= 0.883) and 98.5 kj/mol (r²= 0.878) for isoenzyme a and 13.9°C (r²= 0.990) and 157.1 kj/mol (r²= 0.989) for isoenzyme b, respectively. Inhibitory effect of l-cysteine and sodium disulphide differed from each other.
关键词：White cherry; polyphenol oxidase; enzymatic browning; kinetics; thermal inactivation