Elucidating the molecular mechanisms in the development of such a devastating neurodegenerative disorder as Alzheimer's disease (AD) is currently one of the major challenges of molecular medicine. Evidence strongly suggests that the development of AD is due to the accumulation of amyloid β (Aβ) oligomers; therefore, understanding the molecular mechanisms defining the conversion of physiologically important monomers of Aβ proteins into neurotoxic oligomeric species is the key for the development of treatments and preventions of AD. However, these oligomers are unstable and unavailable for structural, physical, and chemical studies. We have recently developed a novel flexible nano array (FNA)-oligomer scaffold approach in which monomers tethered inside a flexible template can assemble spontaneously into oligomers with sizes defined by the number of tethered monomers. The FNA approach was tested on short decamer Aβ(14-23) peptides which were assembled into dimers and trimers. In this paper, we have extended our FNA technique for assembling full-length Aβ42 dimers. The FNA scaffold enabling the self-assembly of Aβ42 dimers from tethered monomeric species has been designed and the assembly of the dimers has been validated by AFM force spectroscopy experiments. Two major parameters of the force spectroscopy probing, the rupture forces and the rupture profiles, were obtained to prove the assembly of Aβ42 dimers. In addition, the FNA-Aβ42 dimers were used to probe Aβ42 trimers in the force spectroscopy experiments with the use of AFM tips functionalized with FNA-Aβ42 dimers and the surface with immobilized Aβ42 monomers. We found that the binding force for the Aβ42 trimer is higher than the dimer (75 ± 7 pN vs. 60 ± 3 pN) and the rupture pattern corresponds to a cooperative dissociation of the trimer. The rupture profiles for the dissociation of the Aβ42 dimers and trimers are proposed. Prospects for further extension of the FNA-based approach for probing of higher order oligomers of Aβ42 proteins are discussed.

中文翻译：

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淀粉样β42二聚体和三聚体的AFM探测。

阐明破坏性神经退行性疾病如阿尔茨海默氏病（AD）的发展过程中的分子机制是分子医学的主要挑战之一。有证据表明，AD的发展是由于淀粉样蛋白β（Aβ）低聚物的积累引起的。因此，了解定义Aβ蛋白的重要生理单体转化为神经毒性寡聚物种的分子机制是发展AD治疗和预防的关键。但是，这些低聚物不稳定，无法用于结构，物理和化学研究。我们最近开发了一种新颖的柔性纳米阵列（FNA）-低聚物支架方法，其中，在柔性模板内束缚的单体可以自发组装成寡聚物，其尺寸由束缚单体的数量定义。FNA方法在组装成二聚体和三聚体的短decamerAβ（14-23）肽上进行了测试。在本文中，我们扩展了FNA技术来组装全长Aβ42二聚体。已经设计了能够从束缚的单体物种自组装Aβ42二聚体的FNA支架，并且已通过AFM力谱实验验证了二聚体的组装。获得了力谱探测的两个主要参数，断裂力和断裂轮廓，以证明Aβ42二聚体的组装。此外，在力谱实验中，使用FNA-Aβ42二聚体探测Aβ42三聚体，使用FNA-Aβ42二聚体功能化的AFM尖端和固定有Aβ42单体的表面。我们发现，Aβ42三聚体的结合力高于二聚体（75±7 pN对60±3 pN），并且破裂模式对应于三聚体的协同解离。提出了Aβ42二聚体和三聚体解离的断裂曲线。讨论了进一步扩展基于FNA的方法来探测Aβ42蛋白的高级寡聚体的前景。60±3 pN），并且破裂模式对应于三聚体的协同解离。提出了Aβ42二聚体和三聚体解离的断裂曲线。讨论了进一步扩展基于FNA的方法来探测Aβ42蛋白的高级寡聚体的前景。60±3 pN），并且破裂模式对应于三聚体的协同解离。提出了Aβ42二聚体和三聚体解离的断裂曲线。讨论了进一步扩展基于FNA的方法来探测Aβ42蛋白的高级寡聚体的前景。