MECHANISTIC STUDIES OF ELECTRON CAPTURE DISSOCIATION BY DEUTERIUM LABELING

氘标记电子捕获离解的机理研究

• 批准号: 7601992
• 负责人: PETER B. O'CONNOR
• 金额: $ 0.97万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-03 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7601992
• 关键词: Carbon; Cations; Computer Retrieval of Information on Scientific Projects Database; Cyclic Peptides; Data; Deuterium; Dissociation; Electrons; Free Radicals; Funding; Glycine; Grant; Hydrogen; Institution; Ions; Isotopes; Kinetics; Label; Life; Mediating; Paper; Peptides; Publishing; Research; Research Personnel; Resources; SHFM1 gene; Site; Source; Testing; United States National Institutes of Health; abstracting; migration; research study; synthetic peptide

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our recent data on ECD of cyclic peptides implied extensive free-radical mediated secondary fragmentation was occurring. In retrospect, the mere observation of the [M+2H]1+ radical ion resulting from the electron capture implies the existence of long lived ( 1 second) radical cations. Since radicals are known to be highly unstable, and since the previous data on ECD of cyclic peptides implied extensive rearrangment, a simple experiment was devised to test this hypothesis. A pair of synthetic peptides were purchased which contained 4 glycine residues. In one peptide, the glycines were deuterium labeled on the alpha carbon thus creating D2-glycine. The other peptide used normal glycine. If a long lived radical undergoes extensive rearrangment, it was expected that the radical will abstract hydrogens and deuteriums indiscriminately from the alpha carbon sites as the radical migrates up and down the peptide. There is likely to be a kinetic isotope effect that will slow down the migration of the deuterium, but this is unlikely to be observable on a 1 second timescale. ECD of the normal versus D2-Glycine modified peptide showed deuterium scrambling which implies that the radical does rearrange and migrate via hydrogen (or deuterium) abstraction from the alpha carbons (of glycine at least). After much effort and many revisions, this paper was finally published in spring 2006.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们最近关于环肽ECD的数据表明，正在发生广泛的自由基介导的二级断裂。 回顾过去，仅仅观察到由电子捕获产生的[M+2 H]1+自由基离子意味着存在长寿命（1秒）自由基阳离子。 由于自由基是非常不稳定的，并且由于先前关于环肽的ECD的数据暗示了广泛的依赖性，因此设计了一个简单的实验来测试这一假设。 购买一对含有4个甘氨酸残基的合成肽。 在一种肽中，甘氨酸在α碳上被氘标记，从而产生D2-甘氨酸。 另一种肽使用正常的甘氨酸。 如果一个长寿命的自由基经历了广泛的reflection，预计自由基将抽象的氢和氘不加区别地从α碳网站作为自由基迁移的肽。 很可能存在一种动力学同位素效应，这将减缓氘的迁移，但这不太可能在1秒的时间尺度上观察到。 正常肽与D2-甘氨酸修饰肽的ECD显示氘扰乱，这意味着自由基确实通过从α碳（至少甘氨酸的α碳）夺取氢（或氘）而重排和迁移。 经过多次努力和修改，这篇论文终于在2006年春天发表。