Amyloid oligomers are considered the most neurotoxic species of amyloid aggregates. Spontaneous assembly of amyloids into aggregates is recognized as a major molecular mechanism behind Alzheimer’s disease and other neurodegenerative disorders involving protein aggregation. Characterization of such oligomers is extremely challenging but complicated by their transient nature. Previously, we introduced a flexible nanoarray (FNA) method enabling us to probe dimers assembled by the amyloid β (14-23) [Aβ (14-23)] peptide. The study presented herein modifies and enhances this approach to assemble and probe trimers of Aβ (14-23). A metal-free click chemistry approach was used, in which dibenzocyclooctyne (DBCO) groups were incorporated at selected sites within the FNA template to click Aβ (14-23) monomers at their terminal azide groups. Atomic force microscopy (AFM) force spectroscopy was employed to characterize the assemblies. The force measurement data demonstrate that the dissociation of the trimer undergoes a stepwise pattern, in which the first monomer dissociates at the rupture force ∼48 ± 2.4 pN. The remaining dimer ruptures at the second step at a slightly larger rupture force (∼53 ± 3.2 pN). The assembled trimer was found to be quite dynamic, and transient species of this inherently dynamic process were identified.

中文翻译：

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使用束缚的聚合物纳米阵列探测淀粉样β三聚体内的分子间相互作用。

淀粉样蛋白低聚物被认为是淀粉样蛋白聚集体的最具神经毒性的种类。淀粉样蛋白自发组装成聚集体被认为是阿尔茨海默氏病和其他涉及蛋白质聚集的神经退行性疾病的主要分子机制。此类低聚物的表征极具挑战性，但由于其瞬时性质而变得复杂。以前，我们引入了柔性纳米阵列（FNA）方法，使我们能够探测由淀粉样蛋白β（14-23）[Aβ（14-23）]肽组装的二聚体。本文介绍的研究修改并增强了该方法来组装和探测Aβ三聚体（14-23）。使用了一种无金属的点击化学方法，其中在FNA模板内的选定位置结合了二苯并环辛炔（DBCO）基团，以在其末端叠氮化物基团处点击Aβ（14-23）单体。原子力显微镜（AFM）力光谱用于表征组件。力的测量数据表明，三聚体的解离呈逐步模式，其中第一单体在〜48±2.4 pN的断裂力下解离。剩下的二聚体在第二步以稍大的破裂力（〜53±3.2 pN）破裂。发现组装的三聚体是相当动态的，并且鉴定了该固有动态过程的瞬时物种。