不同保护剂处理对木瓜蛋白酶活性和稳定性的影响

Effect of Different Protective Agent Treatments on Papain Activity and Stability

关键词:  木瓜蛋白酶  焦亚硫酸钠  L-半胱氨酸  谷胱甘肽  氧化还原反应

Key words:  papain  sodium metabisulfite  L-cysteine  glutathione  redox reaction

摘要:

为提高木瓜蛋白酶活力的稳定性，选择不同的醇类、糖类和化合物质作为保护剂进行筛选，以酶活力的高低以及保存时间长短作为评价的标准。经过初筛得到谷胱甘肽、硫代硫酸钠、焦亚硫酸钠、乙二胺四乙酸（Ethylene Diamine Tetraacetic Acid，EDTA）、L-半胱氨酸有一定的保护作用；又延长保存时间观察酶活力，发现焦亚硫酸钠、L-半胱氨酸、谷胱甘肽具有稳定木瓜蛋白酶的作用，与对照组相比，两个月内酶活力保持不下降。其中焦亚硫酸钠最适保护浓度为0.1%；L-半胱氨酸最适保护浓度为0.6%；谷胱甘肽最适保护浓度为0.4%。根据保存时间的长短和酶活力高低，三种保护剂对木瓜蛋白酶保护作用从大到小的顺 序是焦亚硫酸钠>L-半胱氨酸>谷胱甘肽。焦亚硫酸钠、L-半胱氨酸、谷胱甘肽都具有较好的氧化还原反应，能够改变蛋白质的结构，影响木瓜蛋白酶的活性基团来稳定酶活力，延长酶的保存日期，对于木瓜酶产业的发展具有重要意义。

Abstract:

In order to improve the stability of papain activity, different alcohols, sugars and compounds were selected as protective agents for screening, and the level of enzyme activity and the length of storage time were used as the evaluation criteria. After preliminary screening, Glutathione,Sodium Thiosulfate, Na2S2O5, Ethylene Diamine Tetraacetic Acid (EDTA)and L-Cys were obtained to have certain protective effects. The storage time was extended to observe the enzyme activity, and it was found that Na2S2O5, L-Cys and Glutathione had the effect of stabilizing papain, and the enzyme activity did not decrease for two months compared with the control group. Among them, the optimal protective concentrations of Na2S2O5,L-Cys and Glutathione were 0.1%, 0.6% and 0.4%, respectively. According to the length of storage time and enzyme activity, the protective effect of the three protectants on papain from large to small was Na2S2O5>L-Cys> Glutathione. Na2S2O5, L-Cys and Glutathione all have good redox reactions, which can change the structure of proteins, affects the active groups of papain to stabilize enzyme activity and prolong the shelf life of enzymes, which is of great significance for the development of papain industry.