Abstract Benefits and drawbacks of combining in-vacuo/solution methylation with ESI-DMS-MS analysis are demonstrated in studies with the peptides pentaalanine and [Glu1] fibrinopeptide B. Methylation introduces a quaternary ammonium at the N-terminus of the peptide and changes the number of protonation sites. This has allowed the comparative quantification of sensitivity and selectivity with and without methylation. The transformation of the protonation site in pentaalanine to a quaternary ammonium was observed to reduce DMS selectivity and this was attributed to a weaker ion/modifier interaction. On the other hand, sensitivity was increased and this was attributed to the elimination of ion loss by proton transfer to the modifier. Methylation of [Glu1] fibrinopeptide B was observed not to change the charge state as one protonation site is displaced by a quaternary ammonium. Sensitivity was increased due to suppression of proton transfer to the modifier. Selectivity was not significantly affected in this case as ion/modifier interaction was maintained through the additional protonation site. Our study was conducted with 5 different modifiers and some of their mixtures.

中文翻译：

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甲基化作为一种​​提高肽分析灵敏度和选择性的策略，使用差分迁移谱 (DMS)

摘要 真空/溶液甲基化与 ESI-DMS-MS 分析相结合的优缺点在肽五丙氨酸和 [Glu1] 纤维蛋白肽 B 的研究中得到证明。甲基化在肽的 N 端引入季铵并改变质子化位点的数量。这使得可以对有和没有甲基化的灵敏度和选择性进行比较量化。观察到戊丙氨酸中质子化位点向季铵的转化会降低 DMS 的选择性，这归因于较弱的离子/改性剂相互作用。另一方面，灵敏度增加，这归因于通过质子转移到改性剂消除了离子损失。观察到 [Glu1] 纤维蛋白肽 B 的甲基化不会改变电荷状态，因为一个质子化位点被季铵取代。由于抑制了质子转移到改性剂，灵敏度增加。在这种情况下，选择性没有受到显着影响，因为通过额外的质子化位点保持了离子/改性剂的相互作用。我们的研究是用 5 种不同的改性剂和它们的一些混合物进行的。