Understanding the aggregation selectivity of peptide fragments of full‐length proteins in aqueous solutions with ionic liquids (ILs) could facilitate the elucidation of the relationship between the IL‐protein interactions and structural behavior of intrinsically disordered proteins (IDPs) such as amyloid β protein following the addition of ILs. In the present study, we investigate structural changes in peptide fragment 1‐11 (Aβ_1‐11) of amyloid β protein in aqueous solutions with two ILs including 1‐butyl‐3‐methylimidazolium thiocyanate ([bmim][SCN]) and ethylammonium nitrate (EAN) using optical spectroscopy. The addition of [bmim][SCN], which exhibits strong protein denaturant ability, induced the formation of an intermolecular β‐sheet structure (aggregation), while the addition of EAN, which has a weaker denaturant ability compared with [bmim][SCN], did not cause aggregation. Since the role of cations is related to the ability to mask the charged residues of Aβ_1‐11, the aggregation selectivity of Aβ_1‐11 depends on the anionic species and anions with high denaturation ability enhanced aggregation. Our results demonstrated that the structural change in peptide fragment in aqueous IL solutions could be used to evaluate the relationship between the IL‐protein interactions and aggregation selectivity in IDPs in aqueous IL solutions.

中文翻译：

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淀粉样β1-11肽在离子液体水溶液中的聚集选择性

了解具有离子液体（IL）的水溶液中全长蛋白质的肽片段的聚集选择性可能有助于阐明IL-蛋白质相互作用与内在无序蛋白质（IDP）（例如淀粉样β蛋白）的结构行为之间的关系IL的添加。在本研究中，我们调查肽片段1-11（A结构变化β _1-11）的淀粉状蛋白β含有两个IL的水溶液中的蛋白质，包括1-丁基-3-甲基咪唑硫氰酸盐（[bmim] [SCN]）和硝酸乙基铵（EAN）的光谱。加入具有较强蛋白质变性能力的[bmim] [SCN]会诱导形成分子间的β-折叠结构（聚集），而加入EAN则具有比[bmim] [SCN]弱的变性能力]，则不会引起聚集。由于阳离子的作用有关，掩盖A的带电荷残基的能力β _1-11，A的聚集选择性β _1-11取决于阴离子种类和具有高变性能力的阴离子增强的聚集作用。我们的结果表明，IL水溶液中肽片段的结构变化可用于评估IL水溶液中IDP中IL-蛋白质相互作用与聚集选择性之间的关系。