THE EFFECT OF FIXED CHARGE MODIFICATION ON ECD

固定收费修改对 ECD 的影响

• 批准号: 7955975
• 负责人: PETER B. O'CONNOR
• 金额: $ 0.09万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-06-01 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7955975
• 关键词: American; Amyloid beta-Protein; Biology; Charge; Computer Retrieval of Information on Scientific Projects Database; Electrons; Free Radicals; Frequencies; Funding; Generations; Grant; Institution; Ions; Journals; Label; Location; Mass Spectrum Analysis; Medicine; Modification; Nature; Pathway interactions; Peptides; Publishing; Research; Research Personnel; Resources; Role; SHFM1 gene; Side; Site; Societies; Source; United States National Institutes of Health; Vertebral column

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. ECD studies of two modified Amyloid beta peptides (20-29 and 25-35) were performed to investigate the role of H+ radicals in the ECD of peptide ions and the free radical cascade (FRC) mechanism. 2,4,6-trimethylpyridinium (TMP) was used as the fixed charge tag, which has the potential of simultaneously trapping the originally formed radical upon electron capture and inhibiting the H+ generation. Unlabeled, singly-labeled, and doubly-labeled peptides were each analyzed by ECD. It was found that both the number and locations of the fixed charge groups influenced the backbone and side-chain cleavages of these peptides in ECD. The frequency and extent of backbone cleavages decreased and those of side-chain cleavages increased with the addition of fixed charge tags. A doubly-labeled peptide with tags spaced far apart produced fewer multiple side-chain cleavages, but slightly more backbone cleavages than the one with neighboring tags. Despite the non-protonated nature of all charged sites in doubly-labeled peptide ions, several low abundance c and z+ ions were still observed in their ECD spectra. Thus, while H+ transfer may be important for the N-C(alpha) bond cleavage, there also exist other pathways. Finally, it appeared that the presence of this particular radical trap merely inhibited but did not eliminate the FRC pathway which most likely proceeded via H+ abstraction through space and produced numerous sidechain and backbone cleavages. This study has been recently published (Li et al., 2008) in the Journal of the American Society for Mass Spectrometry, 2008, 19, 1514-1526.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 对两种修饰的淀粉样β肽（20-29和25-35）进行ECD研究，以研究H+自由基在肽离子ECD中的作用以及自由基级联（FRC）机制。 2,4,6-三甲基吡啶鎓（TMP）被用作固定电荷标签，其具有在电子捕获时捕获最初形成的自由基并抑制H+产生的潜力。未标记的、单标记的和双标记的肽均通过 ECD 进行分析。研究发现，固定电荷基团的数量和位置都会影响 ECD 中这些肽的主链和侧链裂解。随着固定电荷标签的添加，主链裂解的频率和程度降低，侧链裂解的频率和程度增加。标签间隔较远的双标记肽产生的多重侧链裂解较少，但主链裂解比具有相邻标签的肽略多。尽管双标记肽离子中所有带电位点均具有非质子化性质，但在其 ECD 光谱中仍观察到一些低丰度的 c 和 z+ 离子。因此，虽然 H+ 转移对于 N-C(α) 键断裂可能很重要，但还存在其他途径。最后，这种特殊自由基陷阱的存在似乎只是抑制但没有消除 FRC 途径，该途径很可能通过空间中的 H+ 抽象进行，并产生大量侧链和主链裂解。这项研究最近发表在美国质谱学会杂志 (Journal of the American Society for Mass Spectrometry), 2008, 19, 1514-1526 上 (Li et al., 2008)。