Properties of wheat bran polyphenol oxidase.
Properties of wheat bran polyphenol oxidase.
复制标题
麦麸多酚氧化酶的特性。
DOI：
10.1002/food.200300193
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Z. Söylemez
中科院分区：
文献类型：
--
作者：
Çiğdem Soysal;Z. Söylemez
小麦麸皮多酚氧化酶（PPO）催化4-甲基邻苯二酚的氧化。天然存在于粗提物中的酚类化合物作为内源性底物发挥作用，粗提物的活性需要校正。活性与酶浓度在高底物浓度下得到线性图，而在低底物浓度下得到非线性图，这证明了内源性底物的存在。硅藻土吸附和聚乙烯吡咯烷酮（PVPP）萃取导致酚类的去除。吸附的PPO硅藻土上产生的比活性增加了4倍，而提取与PVPP产生的比活性增加了2.5倍，与粗提取物相比。PPO催化氧化的动力学符合Michaelis-Menten模型; Km和Vmax值分别为218 mM和99 μ M/min。该酶被乙醇、二硫苏糖醇（DTT）和异丙肾上腺素抑制，并在高达90 ℃的温度下表现出热稳定性。该酶的最适pH为5.0。
Polyphenol oxidase (PPO) obtained from wheat bran catalyzed the oxidation of 4-methyl catechol. Phenolic compounds found naturally in crude extract played role as an endogeneous substrate and activity of crude extract needed correction. Activity versus enzyme concentration gave a linear plot at high substrate concentration whereas a nonlinear plot was obtained at low substrate concentration which proved the presence of endogeneous substrate. Adsorption on celite and extraction with polyvinylpyrrolidone (PVPP) caused the removal of phenols. Adsorption of PPO on celite yielded a 4-fold increase in specific activity whereas extraction with PVPP yielded a 2.5-fold increase in specific activity compared to the crude extract. The kinetics of PPO catalyzed oxidation obeyed Michaelis-Menten model; Km and Vmax values were found as 218 mM and 99 microM/min, respectively. The enzyme was inhibited by ethyl alcohol, dithiothreitol (DTT) and isoproterenol and exhibited heat stability up to a temperature of 90 degrees C. The optimum pH of the enzyme was found to be 5.0.