Melting of Hemoglobin in Native Solutions as measured by IMS-MS
Melting of Hemoglobin in Native Solutions as measured by IMS-MS
复制标题
通过 IMS-MS 测量天然溶液中血红蛋白的熔化
DOI：
10.1021/acs.analchem.9b05561
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发表时间：
2020
影响因子：
7.4
通讯作者：
Clemmer, David E.
中科院分区：
文献类型：
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作者：
Woodall, Daniel W.;Brown, Christopher J.;Raab, Shannon A.;El-Baba, Tarick J.;Laganowsky, Arthur;Russell, David H.;Clemmer, David E.
热诱导的血红蛋白四聚体（人）在水溶液（150 mM醋酸铵）的四级结构的结构转变进行了研究，使用变温电喷雾电离（vt-ESI）技术结合离子迁移谱（IMS）和质谱（MS）测量。在较低的溶液温度（28 - 40 °C）下，异四聚体（α2β2）复合物是观察到的最丰富的物质。当溶液温度升高时，该组装体解离成异二聚体（全αβ形式），然后在较高温度（>60 °C）下最终形成不溶性聚集体。除了完整的αβ形式外，还观察到一小部分αβ二聚体，仅含有单个血红素配体，并具有映射到β亚基的二氧化修饰。氧化的异二聚体比未修饰的全异二聚体更不稳定。β亚基的Cys 93残基是双氧化的主要位点。这种翻译后修饰与αβ亚基界面和血红素结合位点非常接近，表明这种修饰与血红素的丢失和蛋白质稳定性降低有关。这些物种的电荷状态和碰撞截面的变化表明，四聚体和二聚体有利于在高温下（在解离占主导地位的温度之前）不太紧凑的结构。
Thermally induced structural transitions of the quaternary structure of the hemoglobin tetramer (human) in aqueous solution (150 mM ammonium acetate) were investigated using a variable temperature electrospray ionization (vt-ESI) technique in combination with ion mobility spectrometry (IMS) and mass spectrometry (MS) measurements. At low solution temperatures (28 to ∼40 °C), a heterotetrameric (α2β2) complex is the most abundant species that is observed. When the solution temperature is increased, this assembly dissociates into heterodimers (holo αβ forms) before ultimately forming insoluble aggregates at higher temperatures (>60 °C). In addition to the holo αβ forms, a small population of αβ dimers containing only a single heme ligand and having a dioxidation modification mapping to the β subunit are observed. The oxidized heterodimers are less stable than the unmodified holo-heterodimer. The Cys93residue of the β subunit is the primary site of dioxidation. The close proximity of this post translational modification to both the αβ subunit interface and the heme binding site suggests that this modification is coupled to the loss of the heme and decreased protein stability. Changes in the charge state and collision cross sections of these species indicate that the tetramers and dimers favor less compact structures at elevated temperatures (prior to temperatures where dissociation dominates).