非酶糖基化对α-synuclein分子构象的影响  

Nonenzymatic Glycation of α-Synuclein and Changes in Its Conformation

作　　者：盛之玲[1,2,3] 刘延英[1] 陈岚[1] 赫荣乔[1] 

机构地区：[1]中国科学院生物物理研究所,北京100101 [2]中国科学院研究生院,北京100049 [3]郑州大学医学院,郑州450052

出　　处：《生物化学与生物物理进展》2008年第10期1202-1208,共7页Progress In Biochemistry and Biophysics

基　　金：国家自然科学基金(90206041,30570536);国家重点基础研究发展计划(973)(2006CB500703);中国科学院基金(KSCX2-YW-R-119)资助项目~~

摘　　要：将纯化后的α-synuclein分别与果糖和葡萄糖孵育,通过内源荧光、非酶糖基化衍生物特征荧光、圆二色光谱以及电子显微镜等技术进行检测发现:α-synuclein与还原糖共同孵育后,308nm内源荧光强度明显降低,同时在447nm产生一个非酶糖基化衍生物特征荧光.与果糖孵育的蛋白质样品其非酶糖基化特征荧光的出现速度快于葡萄糖孵育样品.内源荧光与非酶糖基化特征荧光之间存在能量传递现象,提示Tyr残基与非酶糖基化特征荧光发色团在空间距离上彼此接近.圆二色光谱测定结果显示,α-synuclein与果糖孵育后,其α-螺旋含量增加.非酶糖基化的α-synuclein在电子显微镜下表现为短纤维状.非酶糖基化可以诱导α-synuclein蛋白分子聚集,且果糖较葡萄糖更容易使α-synuclein发生非酶糖基化.以上结果提示,非酶糖基化似乎可以导致α-synuclein在细胞内的错误折叠和分子聚集.During the incubation of purified α-synuclein with fructose or glucose, it was observed that the protein intrinsic fluorescence at 308 nm decreased while the fluorescence of glycated derivant at 447 nm increased. This fluorescence representing nonenzymatic glycation of α-synuclein was more rapidly formed in the presence of fructose than that of glucose. Interestingly, an energy transfer could be observed from the intrinsic fluorescence to the nonenzymatic glycating fluorescence, suggesting a near distance between Tyr residues and the nonenzymatic glycated derivant. Experiments using circular dichroism showed that the content of α-helix of nonenzymatic glycated α-synuclein was increased during the nonenzymatic glycation, especially incubated with fructose. The nonenzymatic glycated α-synuclein was in some rod-like filaments under the electronic microscope. That is to say, nonenzymatic glycation induces the conformational changes of α-synuclein which is more vulnerable to the nonenzymatic glycation of fructose. It appears that nonenzymatic glycation induces α-synuclein misfolding and probably aggregation in cell.

关 键 词：非酶糖基化 α—synuclein 分子构象 特征荧光 错误折叠 分子聚集 神经退行性疾病 

分 类 号：Q5[生物学—生物化学] Q6