Unraveling the Photoluminescence Response of Light-Switching Ruthenium(II) Complexes Bound to Amyloid-β
Unraveling the Photoluminescence Response of Light-Switching Ruthenium(II) Complexes Bound to Amyloid-β
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DOI：
10.1021/ja404850u
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发表时间：
2013-07-24
影响因子：
15
通讯作者：
Marti, Angel A.
中科院分区：
文献类型：
--
作者：
Cook, Nathan P.;Ozbil, Mehmet;Marti, Angel A.
光致发光分子被广泛用于肽聚集的实时监测。在本文中，我们详细介绍了实验和计算建模，以阐明[Ru(bpy)(2)dppz]²⁺与β - 淀粉样蛋白（Aβ(1 - 40)）聚集体之间的相互作用。从单体Aβ到纤维状Aβ的转变在阿尔茨海默病研究中具有重要意义。浓度依赖性实验确定了解离常数为2.1 μM，而等摩尔连续变化法（Job plots）得出每个[Ru(bpy)(2)dppz]²⁺结合的化学计量比为2.6个Aβ单体。我们结合分子对接（刚性和柔性）以及全原子分子动力学（MD）模拟的计算方法预测，缬氨酸18（Val18）和苯丙氨酸20（Phe20）之间的疏水裂缝是一个合理的结合位点，这也可以解释[Ru(bpy)(2)dppz]²⁺在结合时光致发光增强的现象。这个结合位点与纤维轴平行，这与这些复合物在DNA中的结合位点（垂直于DNA轴）形成鲜明对比。在Aβ纤维的边缘可能存在其他结合位点，但在几微米长的Aβ纤维中它们实际上数量很少。通过对缺乏形成结合位点所需氨基酸的Aβ片段（Aβ(25 - 35)）进行结合研究，证实了结合位点的归属。实验和计算工作之间的一致性非常显著，并提供了一个可用于研究淀粉样蛋白结合分子与Aβ相互作用的通用模型。
Photoluminescent molecules are widely used for real-time monitoring of peptide aggregation. In this Article, we detail both experimental and computational modeling to elucidate the interaction between [Ru(bpy)(2)dppz](2+) and amyloid-beta(A beta(1-40)) aggregates. The transition from monomeric to fibrillar A beta is of interest in the study of Alzheimers disease. Concentration-dependent experiments allowed the determination of a dissociation constant of 2.1 mu M, while Job plots provided a binding stoichiometry of 2.6 A beta monomers per [Ru(bpy)(2)dppz](2+). Our computational approach that combines molecular docking (both rigid and flexible) and all-atom molecular dynamics (MD) simulations predicts that the hydrophobic cleft between Val18 and Phe20 is a plausible binding site, which could also explain the increase in photoluminescence of [Ru(bpy)(2)dppz](2+) upon binding. This binding site is parallel to the fibril axis, in marked contrast to the binding site of these complexes in DNA (perpendicular to the DNA axis). Other binding sites may exist at the edges of the A beta fibril, but they are actually of low abundance in an A beta fibril several micrometers long. The assignment of the binding site was confirmed by binding studies in an A beta fragment (A beta(25-35)) that lacked the amino acids necessary to form the binding site. The agreement between the experimental and computational work is remarkable and provides a general model that can be used for studying the interaction of amyloid-binding molecules to A beta.