Collision-Induced Unfolding Is Sensitive to the Polarity of Proteins and Protein Complexes
Collision-Induced Unfolding Is Sensitive to the Polarity of Proteins and Protein Complexes
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DOI：
10.1007/s13361-019-02326-z
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发表时间：
2019-11-01
影响因子：
3.2
通讯作者：
Bush, Matthew F.
中科院分区：
文献类型：
--
作者：
Hong, Seoyeon;Bush, Matthew F.
碰撞诱导展开(CIU)使用离子迁移率来探测蛋白质和非共价复合体的离子结构，作为分析前气相激活程度的函数。CiU可以对结构域结构、异构体身份和结合伙伴敏感，这使得它对许多应用程序都很有吸引力。几乎所有以前的CIU应用都探测到了阳离子。在这里，我们评估了CIU在阴离子中的应用，并比较了阴离子和阳离子的结果。为此，我们开发了一个“相似性分数”，我们用它来量化不同CIU实验结果之间的差异，并评估这些差异相对于潜在测量结果的方差的重要性。所鉴定的阴离子和阳离子之间的许多差异可以归因于阴离子的较低的绝对电荷状态。例如，在整个能量范围内，碰撞截面增加的幅度强烈地依赖于绝对电荷状态。然而，在中等能量范围内，具有相同绝对电荷状态的阴离子和阳离子之间存在显著差异。因此，CIU对蛋白质离子的极性很敏感。基于这些结果，我们认为CIU在区分相似蛋白质或非共价复合体方面的作用也可能依赖于极性。更广泛地说，这些结果表明，类天然阳离子和阴离子的结构和动力学之间的关系值得进一步关注，未来的研究可能会受益于综合两种极性离子的结果。
Collision-induced unfolding (CIU) uses ion mobility to probe the structures of ions of proteins and noncovalent complexes as a function of the extent of gas-phase activation prior to analysis. CIU can be sensitive to domain structures, isoform identities, and binding partners, which makes it appealing for many applications. Almost all previous applications of CIU have probed cations. Here, we evaluate the application of CIU to anions and compare the results for anions with those for cations. Towards that end, we developed a "similarity score" that we used to quantify the differences between the results of different CIU experiments and evaluate the significance of those differences relative to the variance of the underlying measurements. Many of the differences between anions and cations that were identified can be attributed to the lower absolute charge states of anions. For example, the extents of the increase in collision cross section over the full range of energies depended strongly on absolute charge state. However, over intermediate energies, there are significant difference between anions and cations with the same absolute charge state. Therefore, CIU is sensitive to the polarity of protein ions. Based on these results, we propose that the utility of CIU to differentiate similar proteins or noncovalent complexes may also depend on polarity. More generally, these results indicate that the relationship between the structures and dynamics of native-like cations and anions deserve further attention and that future studies may benefit from integrating results from ions of both polarities.