T-80对木瓜蛋白酶酶活和构象的影响  

Effect of T-80 on enzyme activity and configuration of papain

作　　者：程世贤[1] 梁燕燕[2] 龚福忠[2] 

机构地区：[1]广西中医药大学药学院,南宁530001 [2]广西大学化学化学学院,南宁530004

出　　处：《中国科技论文》2015年第18期2141-2144,共4页China Sciencepaper

基　　金：国家自然科学基金资助项目(11405115,11275142)

摘　　要：为探究非离子型表面活性剂与木瓜蛋白酶的作用机理,本文以聚氧乙烯山梨糖醇酐单油酸酯(T-80)为作用主体,采用紫外、荧光和远紫外圆二色等光谱技术研究木瓜蛋白酶-T-80体系在不同pH和不同T-80质量浓度下木瓜蛋白酶的酶活及其构象变化。结果表明:在所考察的pH(6.30、8.00、9.50)条件下,T-80对木瓜蛋白酶酶活有抑制作用,而且pH越高,T-80质量浓度越大,对酶活的抑制作用越强。当T-80质量浓度小于或等于1 bcmc(bcmc为T-80的临界胶束浓度)时,T-80对木瓜蛋白酶的荧光有增强作用,质量浓度越大,增强作用越明显;而当T-80质量浓度大于1bcmc后,T-80对木瓜蛋白酶的荧光则有猝灭作用,质量浓度越大,猝灭作用越强。当T-80质量浓度小于15mg/L时,木瓜蛋白酶的α-螺旋、无规卷曲构型百分数减少,β-折叠、回转构型百分数增加;当T-80质量浓度高于15mg/L后,木瓜蛋白酶的α-螺旋、无规卷曲构型百分数增加,而β-折叠、回转构型百分数减少。木瓜蛋白酶的无规卷曲构型百分数越大,酶活越低,这是T-80对木瓜蛋白酶酶活产生抑制作用的主要原因之一。To investigate the interaction mechanism of non-ionic surfactant and papain,Polyoxyethylene sorbitan monooleate（T-80）was used as subject,and UV-Vis Spectroscopy（UV）,Fluorescence Spectroscopy（FS）and Circular Dichroism（CD）spectroscopy were applied to study the enzyme activity and configuration of papain in different pH values and T-80 concentrations.The results show that under three different pH values（i.e.6.30,8.00,9.50）,T-80 inhibits the enzyme activity of papain,the higher the pH value and T-80 concentration,the greater the inhibition for the enzyme activity.The fluorescence spectrum shows that when T-80 concentrations are lower than 1 bcmc,the fluorescence intensity of papain enhances,while when T-80 concentrations are 1bcmcabove,the fluorescence quenching occurs,and the greater the T-80 concentration,the stronger the quenching.For the secondary configurations,the CD spectrum indicates that when T-80 concentrations are lower than 15mg/L,the percentage of configurations such asα-helix and random coil configurations decrease,but the percentage ofβ-sheet and turning configuration increases.After the T-80 concentrations are 15mg/L above,the percentage ofα-helix and disorder configurations increases,but shows a decrease for turning and random coil configurations.The more the random coil configuration,the lower the papain enzyme activity,this is one of the main reason resulting in inhibition of T-80 on the papain enzyme activity.

关 键 词：木瓜蛋白酶 酶活 构象 T-80 

分 类 号：Q946.5[生物学—植物学]