影响金针菇多酚氧化酶活性因素研究

目的从金针菇中提取多酚氧化酶，并对其特性进行研究．方法采用分光光度法研究温度、pH、抑制剂对金针菇多酚氧化酶活力的影响．结果以邻苯二酚为底物，金针菇多酚氧化酶（Polyphenoloxidase from Flammulina velutipes，FVPPO）的酶促褐变产物在可见光波长295nm处有最大吸收峰；在pH为5．0—6．0范围内酶活力较大；在20—40℃的范围内随着温度升高，酶活性逐渐增强；在40℃时PPO活性最强；抗坏血酸、柠檬酸、EDTA-2Na对金针菇多酚氧化酶的活性都有抑制作用，在同浓度下，对金针菇PPO活性的抑制效果次序为抗坏血酸〉柠檬酸〉EDTA-2Na．结论金针菇多酚氧化酶的最适pH为6．0，最适温度为40℃，抗坏血酸对金针菇PPO活性的抑制作用最强．

On Activity Factors of Polyphenol Oxidase in Flammulina velutipes

Objective Polyphenol oxidase was extracted from Flammulina velutipes, and some properties were studied. Method The effects of temperature, pH and inhibitors on the activities of polyphenol oxidase （PPO） from Flammulina velutipes were studied by using spectrophotometry. Results Using pyrocatechol as the substrate,the product of enzymation brown catalyzed by polyphenol oxidase from Flammulina velutipes shows maximum absorption peak at the visible wavelength of 295 nm;the enzyme exhibited a better activity at the pH range from 5.0 to 6.0 ; the enzyme activity enhanced gradually with the temperature increasing from 20 - 40 ℃ ; the activity of PPO shows the strongest when the optimum temperature was 40 ℃; ascorbic acid, citric acid and EDTA-2Na can inhibit the activity of polyphenol oxidase. Under the same concentration, the order of inhibition effects on PPO was ascorbic acid 〉 citric polyphenol oxidase from Flammulina velutipes acid 〉 EDTA-2Na. Conclusion The optimum pH value for was 6.0; the optimum temperature was at 40 ℃ ; ascorbic acid showed the strongest inhibitory effect on the activity of PPO