The conformation of proteins is closely related to their biological functions, and it is affected by many factors, including the type of cations in solution. However, it is difficult to detect the conformational changes of a protein in situ. As a single-molecule sensing technology, nanopores can convert molecular structural information into analyzable current signals within a reasonable time range. Herein, we detect and analyze the effects of two different types of monovalent cations (Na⁺ and Li⁺) on a model protein bovine serum albumin (BSA) conformation using SiN_x nanopores with different diameters. The quantitative analysis results show that the excluded volume of BSA in LiCl salt solutions is larger than the value in NaCl solution, indicating that Li⁺ is more prone to unfolding the proteins and making them unstable. This study demonstrated that nanopores enable the in situ detection of the structure of proteins at the single-molecule level and provide a new approach for the quantitative analysis of proteins.

中文翻译：

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利用固态纳米孔分析阳离子对蛋白质构象稳定性的影响

蛋白质的构象与其生物学功能密切相关，并受到多种因素的影响，其中包括溶液中阳离子的类型。然而，原位检测蛋白质的构象变化是很困难的。纳米孔作为一种单分子传感技术，可以在合理的时间范围内将分子结构信息转化为可分析的电流信号。在此，我们使用不同直径的SiN _x^{纳米孔检测并分析了两种不同类型的单价阳离子（Na +}和Li ⁺）对模型蛋白牛血清白蛋白（BSA）构象的影响。定量分析结果表明，BSA在LiCl盐溶液中的排除体积大于在NaCl溶液中的值，表明Li ⁺更容易使蛋白质解折叠并使其不稳定。该研究表明，纳米孔能够在单分子水平上原位检测蛋白质的结构，为蛋白质的定量分析提供了新的方法。