Hydration of Guanidinium Ions: An Experimental Search for Like-Charged Ion Pairs
Hydration of Guanidinium Ions: An Experimental Search for Like-Charged Ion Pairs
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DOI：
10.1021/acs.jpclett.9b00268
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发表时间：
2019-03-21
影响因子：
5.7
通讯作者：
Russell, David H.
中科院分区：
文献类型：
--
作者：
Hebert, Michael J.;Russell, David H.
胍盐离子（GdmH（+））在水溶液中能形成稳定的配合物（GdmH（+）/GdmH（+）），尽管它们之间有很强的排斥作用。这些复合物被认为在蛋白质折叠、膜穿透和蛋白质二聚体的形成中起重要作用。虽然GdmH（+）离子是弱水合的，但半经验计算提供的证据表明，这些带相同电荷的络合物是由水分子稳定的，水分子起着重要的结构和能量作用。具体而言，水分子在GdmH（+）/GdmH（+）复合物的GdmH（+）离子以及涉及精氨酸的胍侧链的复合物之间桥接。同电荷配合物的潜在生物学意义已在很大程度上被从头算分子动力学模拟和间接实验证据所证实。我们报告低温离子迁移率质谱结果GdmH（+）/GdmH（+）离子对限制在一个nanodroplet-the第一次直接实验观察这种带电荷的复合物。还观察到第二种电荷类似的复合物，描述为涉及GdmH（+）和H3 O+的水介导的复合物。
Guanidinium ions (GdmH(+)) are reported to form stable complexes (GdmH(+)/GdmH(+)) in aqueous solution despite strong repulsive interactions between the like-charged centers. These complexes are thought to play important roles in protein folding, membrane penetration, and formation of protein dimers. Although GdmH(+) ions are weakly hydrated, semiempirical calculations provide evidence that these like-charged complexes are stabilized by water molecules, which serve important structural and energetic roles. Specifically, water molecules bridge between the GdmH(+) ions of GdmH(+)/GdmH(+) complexes as well as complexes involving the guanidinium side chains of arginine. Potential biological significances of like-charged complexes have been largely confirmed by ab initio molecular dynamics simulations and indirect experimental evidence. We report cryo-ion mobility-mass spectrometry results for the GdmH(+)/GdmH(+) ion pair confined in a nanodroplet-the first direct experimental observation of this like-charged complex. A second like-charged complex, described as a water-mediated complex involving GdmH(+) and H3O+, was also observed.