【摘要】 目的:利用原子力显微镜（AFM）观察β-淀粉样蛋白(Aβ_1-42)在不同聚集状态下的形态结构。方法:制备寡聚体:用六氟异丙醇溶解Aβ_1-42单体,通风干燥后重悬于二甲基亚砜,以PBS稀释后4℃孵育24 h;按常规方法制备Aβ单体和纤维体;用AFM的轻敲模式及相位成像技术观察不同聚集状态Aβ的形态结构,并与单体和纤维体进行比较。结果:在制备寡聚体样本中,可观察到不同形状的Aβ_1-42聚集体,包括球状寡聚体、环状结构、初级原纤维、成熟原纤维体等。初级原纤维呈串珠样链状结构,成熟原纤维呈致密的绳状结构。寡聚体高度为2⁶nm,均值为4.39 nm;原纤维的长度约1μm,高度为1.5 nm⁴ nm。单体分布均匀,呈颗粒状,平均高度为0.65±0.16 nm。纤维长度为2μm以上,高度为2⁴ nm。结论:1用AFM可观察到Aβ单体、纤维和不同聚集状态的中间体,AFM技术是研究蛋白质聚集过程中动态变化的较好工具;2Aβ经PBS处理,可孵育出多种Aβ_1-42中间体:球状体、环状结构和原纤维;3本实验将为研究阿尔茨海默病（AD）的发病机制和开发治疗AD新疗法提供实验依据。更多还原

【Abstract】 Objective: To study the different aggregation morphology of β-amyloid( Aβ_1-42) using atomic force microscope（ AFM）. Methods: Preparation of Aβ Oligomers: Aβ_1-42 peptide was dissolved in cold hexafluoro-2-propanol（ HFIP）. After evaporation,the resulting film was dissolved in anhydrous DMSO and diluted into PBS aged 24 h at 4℃,and prepare Aβ monomers and fibrils by conventional methods. The tapping mode and phase imaging technology of AFM were applied to observe the different aggregation morphology of Aβ_1-42 and compare with monomers and fibrils. Results:AFM images contain a spectrum of Aβ structures,including globular oligomers with diameters varying from 2 to 6 nm（ mean 4. 39 nm）,ring-like structures,protofibrillar structures with lengths less than 1 μm and heights ranging from 1. 5to 4 nm. Primary protofibrils appear to be beaded chain structures,and ripe protofibrils like tight rope-like structures.Granula monomers evenly distributed with an average height of 0. 65 ± 0. 16 nm. The length of fibrils are longer than 2 μm and the height ranged from 2 4 nm. Conclusions: The different aggregation species of Aβ_1-42,such as monomers,fibrils and different state of aggregation intermediates,could be observed using AFM,which is a good tool to study the dynamic changes in the process of protein aggregation; After incubated in PBS,Aβ could express a variety of Aβ_1-42 peptide inter-mediates,including spheroids,ring-like structures and fibrils. The present study will provide experimental evidence for the reasearch of the pathogenesis of AD and the development of new treatments for AD.更多还原