Microsolvation of Charged Sites In Vacuo: Are Native Protein Structures Retained When Charge-Backbone Interactions are Suppressed?

IF 15.6 1区 化学 Q1 CHEMISTRY, MULTIDISCIPLINARY
Lukas R. Benzenberg, Elena Giaretta, Ri Wu*, Despoina Svingou and Renato Zenobi*, 
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Abstract

Native mass spectrometry (nMS) is increasingly used to study proteins and their complexes, providing insights into their stoichiometry, topology, and binding affinities. While noncovalent interactions are thought to largely remain intact after desolvation, protein conformation is highly charge-dependent. Increased Coulomb repulsion typically promotes unfolding and charged surface residues engage in interactions with the protein backbone, disrupting hydrogen bonds and distorting secondary structures. However, the relative contributions of these factors to protein unfolding are not well understood. This study investigates how microsolvation of charged sites using crown ethers affects native-like α-helical structures in the gas phase. Using gas-phase fluorescence spectroscopy and ion mobility-mass spectrometry (IM-MS), we find that crown ethers that bind to lysine side chains promote more compact helical conformations, although the charge state still dictates overall compaction. Crown ether variants with different cavity sizes and electron-rich groups showed similar effects, indicating effective occupation of ammonium cations via hydrogen bonding without attenuating charge–charge interactions. These results suggest that while microsolvation can prevent interactions between charged sites and the protein backbone, it has minimal impact on the overall structure compared to Coulomb repulsion. Comparison with solution-phase data reveals significant helical stretching in the gas phase despite microsolvation, further emphasizing the role of Coulomb repulsion in determining biomolecular structure. This work highlights the value of gas-phase fluorescence spectroscopy as a complementary technique to IM-MS for detecting subtle structural changes.

Abstract Image

真空中带电位点的微溶剂化:当电荷-主链相互作用被抑制时,天然蛋白质结构是否保留?
原生质谱(nMS)越来越多地用于研究蛋白质及其复合物,提供对其化学计量学,拓扑结构和结合亲和力的见解。虽然非共价相互作用被认为在脱溶后基本上保持完整,但蛋白质构象是高度依赖于电荷的。增加的库仑斥力通常会促进展开和带电的表面残基与蛋白质主链的相互作用,破坏氢键并扭曲二级结构。然而,这些因素对蛋白质展开的相对贡献尚未得到很好的理解。本研究探讨了利用冠醚对带电位点的微溶剂化如何影响气相中原生类α-螺旋结构。使用气相荧光光谱和离子迁移质谱(IM-MS),我们发现结合赖氨酸侧链的冠醚促进更紧密的螺旋构象,尽管电荷状态仍然决定了整体的压实。具有不同空腔大小和富电子基团的冠醚变体具有相似的效果,表明在不衰减电荷-电荷相互作用的情况下,通过氢键有效地占领了铵离子。这些结果表明,虽然微溶剂化可以阻止带电位点与蛋白质主链之间的相互作用,但与库仑排斥相比,它对整体结构的影响最小。与溶液相数据的比较表明,尽管微溶剂化,气相中仍有明显的螺旋拉伸,进一步强调了库仑排斥在确定生物分子结构中的作用。这项工作突出了气相荧光光谱作为IM-MS检测细微结构变化的补充技术的价值。
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来源期刊
CiteScore
24.40
自引率
6.00%
发文量
2398
审稿时长
1.6 months
期刊介绍: The flagship journal of the American Chemical Society, known as the Journal of the American Chemical Society (JACS), has been a prestigious publication since its establishment in 1879. It holds a preeminent position in the field of chemistry and related interdisciplinary sciences. JACS is committed to disseminating cutting-edge research papers, covering a wide range of topics, and encompasses approximately 19,000 pages of Articles, Communications, and Perspectives annually. With a weekly publication frequency, JACS plays a vital role in advancing the field of chemistry by providing essential research.
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