Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
Biomolecular Science Institute, Florida International University, Miami, FL 33199, USA.
Anal Methods. 2021 Nov 11;13(43):5216-5223. doi: 10.1039/d1ay01461g.
In the present work, four, well-studied, model peptides (, substance P, bradykinin, angiotensin I and AT-Hook 3) were used to correlate structural information provided by ion mobility and ECD/CID fragmentation in a TIMS-q-EMS-ToF MS/MS platform, incorporporating an electromagnetostatic cell (EMS). The structural heterogeneity of the model peptides was observed by (i) multi-component ion mobility profiles (high ion mobility resolving power, ∼115-145), and (ii) fast online characteristic ECD fragmentation patterns per ion mobility band (∼0.2 min). Particularly, it was demonstrated that all investigated species were probably conformers, involving /-isomerizations at X-Pro peptide bond, following the same protonation schemes, in good agreement with previous ion mobility and single point mutation experiments. The comparison between ion mobility selected ECD spectra and traditional FT-ICR ECD MS/MS spectra showed comparable ECD fragmentation efficiencies but differences in the ratio of radical (˙)/prime (') fragment species (H˙ transfer), which were associated with the differences in detection time after the electron capture event. The analysis of model peptides using online TIMS-q-EMSToF MS/MS provided complementary structural information on the intramolecular interactions that stabilize the different gas-phase conformations to those obtained by ion mobility or ECD alone.
在本工作中，使用了四个经过充分研究的模型肽（P 物质、缓激肽、血管紧张素 I 和 AT 钩 3），将离子淌度和 ECD/CID 碎裂提供的结构信息与 TIMS-q-EMS-ToF MS/MS 平台相关联，其中包含了电磁体单元（EMS）。通过（i）多组分离子淌度谱（高离子淌度分辨能力，∼115-145）和（ii）每个离子淌度带的快速在线特征 ECD 碎裂模式，观察到模型肽的结构异质性（∼0.2 min）。特别地，证明了所有研究的物种可能都是构象体，涉及 X-Pro 肽键的/-异构化，遵循相同的质子化方案，与以前的离子淌度和单点突变实验一致。离子淌度选择的 ECD 光谱与传统的 FT-ICR ECD MS/MS 光谱的比较显示出相当的 ECD 碎裂效率，但自由基（˙）/先导（'）碎片物种（H˙转移）的比例存在差异，这与电子捕获事件后检测时间的差异有关。使用在线 TIMS-q-EMSToF MS/MS 对模型肽的分析提供了关于稳定不同气相构象的分子内相互作用的补充结构信息，这些构象与单独使用离子淌度或 ECD 获得的构象相似。
