Probing the structural characteristics of biomolecular ions in the gas phase following native mass spectrometry (nMS) is of great interest, because noncovalent interactions, and thus native fold features, are believed to be largely retained upon desolvation. However, the conformation usually depends heavily on the charge state of the species investigated. In this study, we combine transition metal ion Förster resonance energy transfer (tmFRET) and ion mobility-mass spectrometry (IM-MS) with molecular dynamics (MD) simulations to interrogate the β-hairpin structure of GB1p in vacuo. Fluorescence lifetime values and collisional cross sections suggest an unfolding of the β-hairpin motif for higher charge states. MD simulations are consistent with experimental constraints, yet intriguingly provide an alternative structural interpretation: preservation of the β-hairpin is not only predicted for 2+ but also for 4+ charged species, which is unexpected given the substantial Coulomb repulsion for small secondary structure scaffolds.

中文翻译：

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探讨去溶剂化后 β-发夹支架的稳定性


在天然质谱 (nMS) 后探测气相中生物分子离子的结构特征非常有意义，因为非共价相互作用以及由此产生的天然折叠特征被认为在去溶剂化后很大程度上得以保留。然而，构象通常在很大程度上取决于所研究物质的电荷状态。在这项研究中，我们将过渡金属离子福斯特共振能量转移 (tmFRET) 和离子淌度质谱 (IM-MS) 与分子动力学 (MD) 模拟相结合，在真空中探究 GB1p 的 β-发夹结构。荧光寿命值和碰撞截面表明β-发夹基序展开以获得更高的电荷态。 MD模拟与实验限制一致，但有趣的是提供了另一种结构解释：β-发夹的保存不仅预测为2+，而且也预测为4+带电物种，考虑到小型二级结构支架的巨大库仑排斥力，这是出乎意料的。