摘要
用基因重组方法制备人类 β 淀粉样蛋白前体 (APP)N端融合蛋白APP2 8～ 12 3 ,应用荧光光谱和圆二色谱技术观测GM 1对APP2 8～ 12 3 构象的影响 .结果表明 :APP2 8～ 12 3 与GM1水溶液和含GM1的脂质体孵育后 ,其荧光强度明显增强 ,最大发射峰位蓝移 2 0nm ;APP2 8～ 12 3 在溶液中的二级结构以α螺旋为主 ,峰位在 2 0 8nm和2 2 2nm ,而APP2 8～ 12 3 与PC/GM 1脂质体或GM 1水溶液孵育后 ,其二级结构虽以α螺旋为主 ,但摩尔椭圆度(θ)值明显增强 .以上结果表明GM1改变了APP2 8～ 12 3 二级结构 ,提示GM1引起APP分子构象的改变 ,可能影响APP分子正常生理功能和跨膜转运过程 .
Alzheimer's disease (AD) is neuropathologically characterized by the presence of extracellular amyloid plaques and intracellular neurofibrillary tangles. The core of senile plaque is amyloid beta-protein (Abeta), which comes from its precursor - amyloid beta-protein precursor (APP). The pQE-APP(28similar to123) plasmids was constructed by gene recombination. The APP(28similar to123) protein was expressed in Escherichia coli and then purified. The purified products were examined for GM1 binding abilities by Western blotting. The effects of GM1 on conformation of APP N-terminus were detected by fluorescence and circular dichroism (CD) techniques. APP(28similar to123) protein could bind with GM1. The intrinsic fluorescence intensity of APP(28similar to123) protein in PC/GM1 vesicles or GM1 solution remarkably increased and the fluorescence peak value blue shifted 20 nm. CD results showed that the major secondary structure of APP(28similar to123) in PBS buffer was alpha-helix. When APP(28similar to123) incubated with PC/GM1 vesicles or GM1 solution, the alpha-helix content increased markedly. These results suggested that GM1 might affect the physiological function of APP and change APP span-membrane process and interfere APP trafficking and internalization by anchoring this molecule on the membrane, which may provide much more substrate for gamma-secretase and enhance Abeta generation on the cells.
出处
《生物化学与生物物理进展》
SCIE
CAS
CSCD
北大核心
2003年第1期107-111,共5页
Progress In Biochemistry and Biophysics
基金
国家自然科学基金资助项目 ( 39870 2 76
39840 0 10 )
国家重点基础研究发展规划项目 (G19990 6 40 0 7) .~~
