Following a Folding Transition with Capillary Electrophoresis and Ion Mobility Spectrometry
Following a Folding Transition with Capillary Electrophoresis and Ion Mobility Spectrometry
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DOI：
10.1021/acs.analchem.6b02424
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发表时间：
2016-11-15
影响因子：
7.4
通讯作者：
Holliday, Alison E.
中科院分区：
文献类型：
--
作者：
Barr, John D.;Shi, Liuqing;Holliday, Alison E.
离子迁移谱（IMS）越来越多地用于描述溶液相现象，最近已被用来建立多个中间体的存在下，在折叠的模型多肽，聚脯氨酸。然而，这些观察是在气相结构上进行的。毛细管电泳（CE）是一种互补的溶液相技术，也是基于带电物质的分离作为大小和电荷的函数。在这里，离子迁移率和毛细管电泳都被用来遵循的折叠转变的13聚体聚脯氨酸肽从全顺式聚脯氨酸I（PPI）构象的全反式聚脯氨酸II（PPII）的构象浸泡在水性溶剂中。同步折叠过程中观察到使用这两种技术。使用离子迁移率观察到八种构象。虽然使用毛细管电泳仅观察到五个峰，但这些峰可以建模为所观察到的IMS构象异构体的总和;这是离子迁移率正在采样溶液相结构的有力证据。CE测量提供了第一个直接的证据，多个折叠中间体存在于溶液中。
Ion mobility spectrometry (IMS) is increasingly used to describe solution-phase phenomena and has recently been used to establish the presence of multiple intermediates during the folding of a model polypeptide, polyproline. These observations, however, are made on gas-phase structures. Capillary electrophoresis (CE) is a complementary solution-phase technique, also based on the separation of charged species as a function of size and charge. Here, both ion mobility and capillary electrophoresis are used to follow the folding transition of a 13-mer polyproline peptide from the all-cis polyproline I (PPI) conformation to the all-trans polyproline II (PPII) conformation upon immersion in aqueous solvent. Synchronous folding processes are observed using both techniques. Eight conformers are observed using ion mobility. Although only five peaks are observed using capillary electrophoresis, these peaks can be modeled as sums of the observed IMS conformers; this is strong evidence that ion mobility is sampling solution-phase structures. CE measurements provide the first direct evidence that multiple folding intermediates are present in solution.