【摘要】 以甜菜夜蛾5龄幼虫为试材提取多酚氧化酶,经40%饱和度硫酸铵沉淀、SephadexG-100凝胶过滤等步骤部分纯化后,总活力回收率为26.67%,酶活力提高8.56倍。以邻苯二酚为底物,测得该酶反应的最佳条件:pH=6.5,T=40℃,米氏常数Km=10.73mmol·L-1。研究了曲酸、香草酸等5种化合物对该酶活力的影响,结果表明,除芦丁外均对其酶活力产生一定的抑制作用,其中以曲酸抑制力最强,其抑制中浓度I50为36.71g·ml-1。曲酸对该酶活力的抑制动力学研究表明,该化合物是典型的可逆竞争型抑制剂,抑制常数Ki=3.55g·ml-1。更多还原

【Abstract】 The kinetic characteristics of polyphenol oxidase (PPO) from Spodoptera exigua (H bner), a importantinsect in horticulture, were studied after the enzyme was partially purified by 40% saturated (NH4)2SO4 and Sephadex G-100gel filtration. The results showed that the activity of enzyme increased by 8.56 folds after purification. The optimum pHwas 6.5, the best working temperature was 40℃,and the Michaelis constant (Km) was 10.73 mmolL-1 for the tested PPO withthe substrate catechol. The effects of 5 compounds as inhibitors of the reaction catalyzed by the enzyme were also tested.Those results indicated that kojic acid was the strongest inhibitor (I50=36.71gml-1) with Ki=3.55gml-1among them, andrutin was the worse in the tested compounds.更多还原