甲基红褪色光度法测定大米中过氧化氢酶活性

Determination of Catalase Activity in Rice by Discoloration Spectrophotometric Method of Methyl Red

探讨甲基红褪色光度法测定过氧化氢酶(CAT)活性新方法。酶促反应后剩余的过氧化氢与甲基红发生褪色反应,Fe^3+能够加速反应进程,褪色程度与酶活性有函数关系。根据酶促反应前后吸光度变化值(ΔA)确定CAT活性(E)。结果表明,在20 min内,酶促反应符合一级动力学反应的特征,E在0~0.12 U/mL范围内与ΔA呈良好的线性关系:ΔA=0.001+2.276E,r=0.998 9,检测限为0.007 U/mL。该方法精密度较好,可应用于不同产地、不同年份大米过氧化氢酶活性测定。

A new discoloration spectrophotometric method was developed for the determination of catalase(CAT)activity.After enzymatic reaction,the remaining catalase and methyl red underwent a decolorizing reaction,which could be accelerated by Fe^3+,and the decolorizing degree was functionally related to the CAT activity.CAT activity(E)was determined according to the absorbance changes(ΔA)before and after the enzymatic reaction.The results showed that the enzymatic reaction was consistent with the characteristics of the first order kinetic reaction within 20 min.In the range of 0~0.12 U/mL,E was linearly correlated toΔA=0.001+2.276 E,r=0.9989,and the limit of detection was 0.007 U/mL.This method had good precision and could be applied to the determination of catalase activity in rice from different place and in different years.