The solution-favored conformations of the 13-residue disordered peptide, indolicidin (Ile1-Leu2-Pro3-Trp4-Lys5-Trp6-Pro7-Trp8-Trp9-Pro10-Trp11-Arg12-Arg13), are evaluated using electrospray ionization (ESI) coupled to ion mobility spectrometry-mass spectrometry (IMS-MS). The ESI-IMS-MS distributions for the dominant [M+4H]4+ ions indicate that three populations of structures coexist in a range of aqueous to non-aqueous solutions (water:dioxane, water:trifluoroethanol, and water:hexafluoroisopropanol). Conformer types and their relative abundances change in response to different solution environments suggesting that the gas phase conformers reflect on the solution populations present in different solvent environments. Collisional activation of isolated gas phase conformations with IMS-IMS-MS experiments provides additional insight about the relative stabilities of different structural types in the absence of solvent. Simulated annealing studies suggest that proline configuration may be important for the presence of multiple conformations.

中文翻译：

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来自 IMS-MS 分析的无序肽 Indolicidin 的多溶液结构

使用电喷雾电离 (ESI) 评估 13 个残基无序肽 indolicidin (Ile1-Leu2-Pro3-Trp4-Lys5-Trp6-Pro7-Trp8-Trp9-Pro10-Trp11-Arg12-Arg13) 的溶液优先构象与离子迁移谱-质谱 (IMS-MS) 耦合。主要 [M+4H]4+ 离子的 ESI-IMS-MS 分布表明三种结构群共存于一系列水溶液到非水溶液（水：二恶烷、水：三氟乙醇和水：六氟异丙醇）中。构象异构体类型及其相对丰度随着不同溶液环境的变化而变化，这表明气相构象异构体反映了不同溶剂环境中存在的溶液种群。使用 IMS-IMS-MS 实验对分离的气相构象进行碰撞激活，可以进一步了解在没有溶剂的情况下不同结构类型的相对稳定性。模拟退火研究表明脯氨酸构型对于多种构象的存在可能很重要。