阿尔茨海默病(Alzheimer’sdisease,AD)是发生在老年人中最常见、最具破坏性的神经退行性疾病。致病标志之一是由淀粉样蛋白-β(Aβ)原纤维组成的老年斑。在具有疾病早期发作的家族性AD(FAD)患者中发现了Aβ中的单突变。每个FADAβ变体的分子细节和性质仍然难以捉摸。这里,我们采用集体光谱技术来检查各种Aβ40原纤维的性质。我们在残基E22(包括E22G)上产生了野生型(WT)原纤维和三个FAD突变体,E22K,E22Q我们通过硫黄素T(ThT)测定法监测原纤维形成,通过傅里叶变换红外和远紫外圆二色性光谱检查二级结构,通过透射电子显微镜成像原纤维形态,并评估ThT结合动力学。在热实验中,我们发现E22K原纤维耐高温,并且比其他纤维保留了显着的β-折叠含量。E22K原纤维种子经高温处理后仍具有播种性能,而WT原纤维种子在处理后受到干扰。因此,在这项研究中,我们证明了E22K突变增加了淀粉样纤维的热稳定性和接种功能。
Alzheimer\'s disease (AD) is the most prevalent and devastating neurodegenerative disease occurred in the elderly. One of the pathogenic hallmarks is senile plaques composed of amyloid-β (Aβ) fibrils. Single mutations resided in Aβ were found in familial AD (FAD) patients that have early onset of the disease. The molecular details and properties of each FAD Aβ variants are still elusive. Here, we employed collective spectroscopic techniques to examine the properties of various Aβ40 fibrils. We generated fibrils of wild type (WT) and three FAD mutants on residue E22 including E22G, E22K, and E22Q. We monitored fibril formation by thioflavin T (ThT) assay, examined secondary structure by Fourier transform infrared and far-UV circular dichroism spectroscopy, imaged fibril morphology by transmission electron microscopy, and evaluated ThT-binding kinetics. In the thermal experiments, we found E22K fibrils resisted to high temperature and retained significant β-sheet content than the others. E22K fibril seeds after high-temperature treatment still possess the seeding property, whereas WT fibril seeds are disturbed after the treatment. Therefore, in this study we demonstrated the mutation at E22K increases the thermal stability and seeding function of amyloid fibrils.