Interpreting the Collision Cross Sections of Native-like Protein Ions: Insights from Cation-to-Anion Proton-Transfer Reactions.
Interpreting the Collision Cross Sections of Native-like Protein Ions: Insights from Cation-to-Anion Proton-Transfer Reactions.
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DOI：
10.1021/acs.analchem.7b01474
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发表时间：
2017-07
影响因子：
7.4
通讯作者：
Kenneth J. Laszlo;M. F. Bush
中科院分区：
文献类型：
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作者：
Kenneth J. Laszlo;M. F. Bush
利用阳离子-阴离子质子转移反应（CAPTR）、离子迁移率、质谱和互补能量依赖实验，探讨了电荷状态对血清白蛋白、链霉亲和素、亲和素和乙醇脱氢酶的天然样阳离子结构的影响。CAPTR产物的碰撞截面（Ω）值均在原始前体阳离子的5.5%以内。每种前体的第一个CAPTR事件产生具有较小Ω值的产物，并且经常表现出由单个CAPTR事件引起的Ω的最大变化幅度。为了研究前体的结构如何影响产物的结构，在CAPTR之前将离子活化为能量的函数。在每种情况下，活化的前体的Ω值随着能量的增加而增加，但是CAPTR产物的Ω值小于活化的前体。为了研究CAPTR产物的稳定性，在离子迁移之前立即活化产物。这些结果表明，具有更小或更大Ω值的额外结构可以被填充，并且这些离子的结构和稳定性最强烈地依赖于蛋白质的身份和产物的电荷状态，而不是前体的电荷状态或CAPTR事件的数量。总之，这些结果表明，最初存在于类天然离子上的过量电荷对其Ω值具有适度但有时具有统计学显著性的影响。因此，当使用实验Ω值来阐明溶液中的结构时，应考虑电荷态的潜在贡献。
The effects of charge state on structures of native-like cations of serum albumin, streptavidin, avidin, and alcohol dehydrogenase were probed using cation-to-anion proton-transfer reactions (CAPTR), ion mobility, mass spectrometry, and complementary energy-dependent experiments. The CAPTR products all have collision cross-section (Ω) values that are within 5.5% of the original precursor cations. The first CAPTR event for each precursor yields products that have smaller Ω values and frequently exhibit the greatest magnitude of change in Ω resulting from a single CAPTR event. To investigate how the structures of the precursors affect the structures of the products, ions were activated as a function of energy prior to CAPTR. In each case, the Ω values of the activated precursors increase with increasing energy, but the Ω values of the CAPTR products are smaller than the activated precursors. To investigate the stabilities of the CAPTR products, the products were activated immediately prior to ion mobility. These results show that additional structures with smaller or larger Ω values can be populated and that the structures and stabilities of these ions depend most strongly on the identity of the protein and the charge state of the product, rather than the charge state of the precursor or the number of CAPTR events. Together, these results indicate that the excess charges initially present on native-like ions have a modest, but sometimes statistically significant, effect on their Ω values. Therefore, potential contributions from charge state should be considered when using experimental Ω values to elucidate structures in solution.