【摘要】 经35%饱和度硫酸铵分级沉淀,将舞毒蛾(Lymantria dispar)酚氧化酶部分纯化。测定该酶最适pH值为6.5,pH在6.5～7.5范围内酶保持稳定的活力。最适温度为35℃,当温度低于25℃时,酶具有稳定的活力。以L-多巴、邻苯二酚和焦性没食子酸为底物时,测定酚氧化酶对底物的专一性,结果表明其Km值分别为3.19、10.74和19.26 mmol.L-1。本实验还研究了有机溶剂对酶活力的影响,结果表明甲醇、乙醇、丙酮和二甲苯对舞毒蛾酚氧化酶都有持续的抑制作用,其IC50分别为0.450、.430、.41和0.13 mmol.L-1。更多还原

【Abstract】 The kinetic propertiesof phenoloxidase(PO,EC.1.14.18.1) fromLymantria dispar,a forestry insect,were determined after the enzyme was partially purified by 35% staturated(NH4)2SO4.The properties of PO showed that the optimum pH was 6.5and the enzyme had a stable activity if the pH reaction system from 6.5 to 7.5,the optimum temperature was 35 ℃,and the enzyme had a stable activity if the temperature reaction system less than 25 ℃,using catechol as substrate.The kinetic parameter for the oxidation of L-DOPA,catechol and pyrogallol by PO was determined,the Km was 3.19、10.74 and 19.26 mmol·L-1,respectively.The effects of some organic methanol,ethanol,acetone and dimethylbenzene solvents on the activity of PO were also studied in the present paper.The results showed that all of them had inhibitory effects on the enzyme activity.The IC50(the inhibitor concent rations leading to 50 % activity lost) of methanol,ethanol and dimethylbenzene were estimated to be 0.45、0.43、0.41and0.13mmol·L-1,respectively.更多还原