红三叶多酚氧化酶特性的研究

Study on the Characteristics of Polyphenol Oxidase from Red Clover

红三叶（Trifolium pretenseL．）多酚氧化酶仅作用于邻苯酚，与对苯酚、间苯酚和一元酚无作用，而且对不同的邻苯酚其活性也表现很大差异，其中以咖啡酸作底物时活性最大。红三叶多酚氧化酶反应的最适pH值为6．5～7．0，最适温度为25～30℃，50℃时热稳定性相对较好。

In red clover （Trifolium pratense） there exists a soluble polyphenol oxidase （PPO）, which oxidizes native phenols to quinines, could bond to proteins, and inhibits proteolysis both in the silo and in the rumen. An observation of the red clover polyphenol oxidase indicated that substrate of PPO was o- diphenol, but not hydroquinone, m-diphenol, or mono-phenol. There were obvious differences between several substrates, and caffeine acid was the highest one for PPO activity. Maximum PPO activities of red clover showed pH 6.5-7.0, and the optimum temperature for the maximum PPO activity was 25-30℃, and heat stability was performed at 50℃.