Are the Gas-Phase Structures of Molecular Elephants Enduring or Ephemeral? Results from Time-Dependent, Tandem Ion Mobility
Are the Gas-Phase Structures of Molecular Elephants Enduring or Ephemeral? Results from Time-Dependent, Tandem Ion Mobility
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DOI：
10.1021/acs.analchem.3c01222
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发表时间：
2023-06-09
影响因子：
7.4
通讯作者：
Bush，Matthew F.
中科院分区：
文献类型：
--
作者：
Zercher，Benjamin P.;Hong，Seoyeon;Bush，Matthew F.
生物分子在气相中的结构稳定性仍然是结构生物学的质谱应用中的重要课题。在这里，我们评估的动力学稳定性的天然蛋白质离子使用时间依赖性，串联离子迁移率（IM）。在这些串联IM实验中，感兴趣的离子在IM的第一维之后被迁移率选择，并被捕获长达1014秒。时间相关的，碰撞截面分布，然后确定从分离的第二维IM。在这些实验中，单体蛋白质离子表现出特定的蛋白质和电荷状态的结构变化，而大的蛋白质复合物没有经历可分辨的结构变化的时间尺度上的这些实验。我们还进行了能量依赖实验，即，碰撞诱导的展开，作为时间依赖性实验的比较，以了解展开的程度。在能量依赖性实验中观察到的碰撞截面值使用高碰撞能量显着大于在时间依赖性实验中观察到的，这表明在时间依赖性实验中观察到的结构保持动力学捕获，并保留一些记忆的溶液相结构。虽然结构演化应考虑高电荷，单体蛋白质离子，这些实验表明，更高质量的蛋白质离子可以在气相中具有显着的动力学稳定性。
The structural stability of biomolecules in the gas phase remains an important topic in mass spectrometry applications for structural biology. Here, we evaluate the kinetic stability of native-like protein ions using time-dependent, tandem ion mobility (IM). In these tandem IM experiments, ions of interest are mobility-selected after a first dimension of IM and trapped for up to ∼14 s. Time-dependent, collision cross section distributions are then determined from separations in a second dimension of IM. In these experiments, monomeric protein ions exhibited structural changes specific to both protein and charge state, whereas large protein complexes did not undergo resolvable structural changes on the timescales of these experiments. We also performed energy-dependent experiments, i.e., collision-induced unfolding, as a comparison for time-dependent experiments to understand the extent of unfolding. Collision cross section values observed in energy-dependent experiments using high collision energies were significantly larger than those observed in time-dependent experiments, indicating that the structures observed in time-dependent experiments remain kinetically trapped and retain some memory of their solution-phase structure. Although structural evolution should be considered for highly charged, monomeric protein ions, these experiments demonstrate that higher-mass protein ions can have remarkable kinetic stability in the gas phase.