Effects of Charge State on the Structures of Serum Albumin Ions in the Gas Phase: Insights from Cation-to-Anion Proton-Transfer Reactions, Ion Mobility, and Mass Spectrometry
Effects of Charge State on the Structures of Serum Albumin Ions in the Gas Phase: Insights from Cation-to-Anion Proton-Transfer Reactions, Ion Mobility, and Mass Spectrometry
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DOI：
10.1021/acs.jpcb.8b08427
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发表时间：
2018-11-01
影响因子：
3.3
通讯作者：
Bush, Matthew F.
中科院分区：
文献类型：
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作者：
Gadzuk-Shea, Meagan M.;Bush, Matthew F.
了解气相中蛋白质的结构对于使用气相测量来推断溶液中蛋白质的性质是至关重要的。使用血清白蛋白作为模型，本研究的目的是扩大我们的理解，这种关系的一个更大的（66 kDa），多结构域蛋白，含有17个内部二硫键。气相离子产生的五个解决方案，保留不同程度的原生结构。离子迁移率（IM）质谱，阳离子到阴离子质子转移反应（CAPTR），和能量依赖IM被用来探测结构，电荷和解决方案之间的关系。越来越多的破坏性条件下产生的离子表现出更高的电荷状态和更大的碰撞截面值。所有CAPTR产物的碰撞截面取决于原始溶液，并在不同程度上取决于产物和前体的电荷状态。例如，变性条件下CAPTR产物的碰撞截面都显著大于原始类天然离子的碰撞截面。从能量依赖性的实验结果表明，从电喷雾电离和它们的CAPTR产品的原始离子的结构是动力学捕获的结果，并取决于在溶液中的高阶结构和二硫键。这项研究建立在我们对溶液条件，二硫键，碰撞截面和电荷之间的关系的理解，一个更大的，多结构域的蛋白质，这可能是适用于未来的生物治疗，共享这些结构特征的表征。
Understanding the structures of proteins in the gas phase is essential for using gas-phase measurements to infer the properties of proteins in solution. Using serum albumin as a model, this study aims to expand our understanding of this relationship for a larger (66 kDa), multidomain protein that contains 17 internal disulfide bonds. Gas-phase ions were generated from five solutions that preserve varying extents of the native structure. Ion mobility (IM) mass spectrometry, cation-to-anion proton-transfer-reactions (CAPTR), and energy-dependent IM were used to probe the relationship between structure, charge, and solution. Ions generated from increasingly disruptive conditions exhibited higher charge states and larger collision cross-section values. The collision cross- sections of all CAPTR products depend on the original solution and to varying extents the charge state of the product and the precursor. For example, the collision cross-sections of CAPTR products from denaturing conditions are all significantly larger than those of the original native-like ions. Results from energy-dependent experiments show that the structures of the original ions from electrospray ionization and their CAPTR products are a consequence of kinetic trapping and depend on higher-order structure and disulfide bonding in solution. This study builds on our understanding of the relationship between solution condition, disulfide bonding, collision cross-section, and charge for a larger, multidomain protein, which may be applicable for future characterization of biotherapeutics that share these structural features.