麻疯树核糖体失活蛋白(curcin)的化学修饰与其活性的关系  

Chemical Modification of Jatropha curcas RIPs(Curcin) and Effect of the Modification on Ralative Activity of Curcin

作　　者：崔维科[1] 赵琦[1] 陈兴春[1] 王克秀[1] 徐莺[1] 唐琳[1] 王胜华[1] 白洁[1] 陈放[1] 

机构地区：[1]四川大学生命科学学院生物资源与生态环境教育部重点实验室

出　　处：《应用与环境生物学报》2006年第3期329-333,共5页Chinese Journal of Applied and Environmental Biology

基　　金：国际合作项目"中国西南地区能源植物的开发和利用"(No.2004DFB00300)~~

摘　　要：通过无细胞体系蛋白合成抑制活性的测定,结合荧光光谱和圆二色谱技术,对麻疯树核糖体失活蛋白(cur-c in)部分氨基酸残基进行特异性化学修饰,探讨维持curc in活性的必需氨基酸基团及修饰对curc in结构的影响.结果表明,组氨酸和半胱氨酸的修饰对活性没有影响.色氨酸和赖氨酸的修饰使curc in的活性分别下降了50%和100%,表明色氨酸和赖氨酸是维持curc in活性的重要残基.精氨酸修饰导致curc in的抑制活性完全丧失,内源荧光强度下降,最大发射波长发生红移,CD谱发生显著变化;表明精氨酸也是维持curc in活性的必需残基,并且对空间结构影响较大,推测对精氨酸的修饰破坏了精氨酸与其它基团的连接,导致curc in分子结构发生改变,失去和底物结合的能力,因而活性丧失.Effects of modifying the amino acids in Jatropha curcas RIPs （curcin） on the conformation and activity of curcin were studied by cell-free translation-inhibitory activity assay, fluorescence and circular dichroism record. The results indicated that the modification of cysteine and histidine residues had no effect on the activity. The modification of lysine and tryptophan residues led to 100% and 50% loss of inhibitor activity respectively, indicating that these two residues were essential to the inhibitory activity. The modification of arginine residues led to a complete loss of inhibitory activity, suggesting that arginine was critical for the inhibitor activity. Fluorescence studies of curcin indicated that the modification of arginine, lysine, tryptophan could quench tryptophan fluorescence with change in Lmax when excited at 280 nm. The far-ultraviolet circular dichroism spectrum showed that the modification of arginine residues affected the conformation of the curcin molecule greatly, indicating that arginine played an important role in curcin＇s conformation. The bonds between the arginine and other residues were destroyed by modification, thus, the substrate could not reach the curcin, and therefore the activity of the curcin was lost. Fig 3, Tab 1, Ref 34

关 键 词：麻疯树核糖体失活蛋白(curcin) 化学修饰 无细胞体系蛋白合成抑制活性 荧光光谱 圆二色谱 

分 类 号：S567.19[农业科学—中草药栽培]