Peptide Dimethylation: Fragmentation Control via Distancing the Dimethylamino Group
作者:Adam J. McShane、Yuanyuan Shen、Mary Joan Castillo、Xudong Yao
DOI:10.1007/s13361-014-0951-7
日期:2014.10.1
Direct reductive methylation of peptides is a common method for quantitative proteomics. It is an active derivatization technique; with participation of the dimethylamino group, the derivatized peptides preferentially release intense a1 ions. The advantageous generation of a1 ions for quantitative proteomic profiling, however, is not desirable for targeted proteomic quantitation using multiple reaction monitoring mass spectrometry; this mass spectrometric method prefers the derivatizing group to stay with the intact peptide ions and multiple fragments as passive mass tags. This work investigated collisional fragmentation of peptides whose amine groups were derivatized with five linear ω-dimethylamino acids, from 2-(dimethylamino)-acetic acid to 6-(dimethylamino)-hexanoic acid. Tandem mass spectra of the derivatized tryptic peptides revealed different preferential breakdown pathways. Together with energy resolved mass spectrometry, it was found that shutting down the active participation of the terminal dimethylamino group in fragmentation of derivatized peptides is possible. However, it took a separation of five methylene groups between the terminal dimethylamino group and the amide formed upon peptide derivatization. For the first time, the gas-phase fragmentation of peptides derivatized with linear ω-dimethylamino acids of systematically increasing alkyl chain lengths is reported.
肽的直接还原性甲基化是定量蛋白质组学中的一种常见方法。这是一种活性衍生化技术;通过二甲氨基基团的参与,衍生化的肽优先释放强烈的a1离子。然而,对于使用多反应监测质谱法的靶向蛋白质定量而言,a1离子的有利生成并不理想;这种质谱方法倾向于使衍生基团保持在完整的肽离子和多个片段上作为被动质量标签。本研究调查了氨酰基被五种线性ω-二甲基氨基酸(从2-(二甲基氨基)-乙酸到6-(二甲基氨基)-己酸)衍生化的肽的碰撞碎裂情况。衍生化胰蛋白酶肽的串联质谱揭示了不同的优先断裂途径。结合能量解析质谱,发现有可能关闭衍生化肽碎裂中末端二甲氨基基团的活性参与。然而,这需要在肽衍生化形成的酰胺与末端二甲氨基基团之间存在五个亚甲基的间隔。本文首次报道了衍生化肽随着系统性增加的烷基链长的线性ω-二甲基氨基酸的气相碎裂情况。