【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 .更多还原

【Abstract】 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 β- protein (Aβ), which comes from its precursor -- amyloid β- protein precursor (APP). The pQE- APP 28～123 plasmids was constructed by gene recombination. The APP 28～123 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 28～123 protein could bind with GM1.The intrinsic fluorescence intensity of APP 28～123 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 28～123 in PBS buffer was α- helix. When APP 28～123 incubated with PC/GM1 vesicles or GM1 solution,the α- 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 γ- secretase and enhance Aβ generation on the cells.更多还原