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Trivalent Metal Ions in Electron-based Dissociation Mass Spectrometry of Peptides

肽电子解离质谱中的三价金属离子

基本信息

批准号：
8626912
负责人：
CAROLYN J CASSADY
金额：
$ 31.12万
依托单位：
UNIVERSITY OF ALABAMA IN TUSCALOOSA
依托单位国家：
美国
项目类别：
财政年份：
2014
资助国家：
美国
起止时间：
2014-02-01 至 2018-01-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): The amino acid sequences of peptides affect their biological activity and, consequently, their utility in the diagnosis and treatment of human health issues. The overall objective of this research is to develop procedures for analyzing and sequencing acidic and neutral peptides by mass spectrometry (MS) using electron-induced dissociation techniques. The focus will be on peptides that are difficult to sequence by current mass spectrometry procedures. The first specific aim involves the use of trivalent metal salts to enhance the protonation of peptides by electrospray ionization (ESI). This will result in doubly protonated ions for peptides that normally only singly protonate. This important because the most common electron-induced fragmentation processes, electron transfer dissociation (ETD) and electron capture dissociation (ECD), require that the precursor ion be a multiply charged cation. Trivalent salts of chromium, Cr(III), have been shown to add a second proton to small peptides that normally singly protonate because they contain only one basic site. Other trivalent metals, such as Fe(III), Rh(III), Al(III), and Eu(III), will also be studied to determine if they enhance protonation for small peptides. The mechanism of this effect with is probed. The salt that produces optimum protonation will be evaluated with mixtures of peptides to determine if peptide ion suppression occurs and also to investigate the impact of the salt on chromatographic separations. The second specific aim is to explore ETD and ECD fragmentation pathways that result from multiply protonated peptide ions generated with trivalent metal ions. The development of a trivalent metal reagent should allow analysis of peptide types that has never been studied before by ETD or ECD; for example, it will now be possible to study acidic peptides and neutral peptides with alkyl side chains. Dissociation mechanisms and fragment ion structures with be probed using multi-stage mass spectrometry, including combinations involving collision-induced dissociation (CID) as a second stage. In addition to enhancing protonation, ESI on mixtures of metal salts and peptides often results in formation of metal-cationized peptide ions. For trivalent metals, these complex ions may have added or removed protons from the peptide, resulting in complexes with charges of 2+, 3+, or 4+. The ability of these complexes to undergo ETD or ECD and yield sequence information for a variety of acidic and neutral peptides will be explored. The lanthanide series of trivalent ions wil be studied in detail. The third member of the series, praseodymium (Pr) with atomic number 59, appears particularly suitable for peptide sequencing. Factors to consider in characterizing the use of trivalent metal ion complexes to sequence peptides include metal electron configuration and ionic radius, the location of the metal ion and the extent of protonation or deprotonation in the precursor and product ions, and the types, number, and locations of amino acid residues in the peptide sequence. Density functional theory (DFT) calculations will be employed to gain insight into the structures and energetics involved in these processes.

描述（由申请人提供）：肽的氨基酸序列影响其生物活性，因此影响其在人类健康诊断和治疗中的效用问题.本研究的总体目标是开发使用电子诱导解离技术通过质谱（MS）分析和测序酸性和中性肽的程序。重点将放在肽是难以测序目前的质谱程序。第一个具体目标涉及使用三价金属盐通过电喷雾电离（ESI）来增强肽的质子化。这将导致通常仅单质子化的肽的双质子化离子。这一点很重要，因为最常见的电子诱导碎裂过程，电子转移解离（ETD）和电子捕获解离（ECD），要求前体离子是多电荷阳离子。铬的三价盐，Cr（III），已经被证明可以向通常单质子化的小肽添加第二个质子，因为它们只包含一个碱性位点。其他三价金属，如Fe（III），Rh（III），Al（III）和Eu（III），也将进行研究，以确定它们是否增强小肽的质子化。并对这种效应的机理进行了探讨。将使用肽混合物评价产生最佳质子化的盐，以确定是否发生肽离子抑制，并研究盐对色谱分离的影响。第二个具体目标是探索ETD和ECD片段化途径，产生的多质子化的肽离子与三价金属离子。三价金属试剂的开发应该允许分析以前从未通过ETD或ECD研究过的肽类型;例如，现在可以研究具有烷基侧链的酸性肽和中性肽。使用多级质谱法探测解离机制和碎片离子结构，包括涉及碰撞诱导解离（CID）作为第二阶段的组合。除了增强质子化，金属盐和肽的混合物上的ESI通常导致形成金属阳离子化的肽离子。对于三价金属，这些络合物离子可能已经从肽中添加或去除质子，产生具有2+、3+或4+电荷的络合物。将探索这些复合物进行ETD或ECD并产生各种酸性和中性肽的序列信息的能力。镧系三价离子将被详细研究。该系列的第三个成员，原子序数为59的镨（Pr），似乎特别适合于肽测序。在表征使用三价金属离子络合物对肽进行测序时要考虑的因素包括金属电子构型和离子半径、金属离子的位置以及前体和产物离子中质子化或去质子化的程度，以及肽序列中氨基酸残基的类型、数量和位置。密度泛函理论（DFT）计算将被用来深入了解这些过程中涉及的结构和能量。