Merged Beam MALDI TOF-TOF Using Ion-Ion Reactions to Determine Structure of

描述（由申请人提供）：使用离子-离子反应确定生物分子结构的合并束MALDI TOF-TOF总结本研究的最终目标是使用正离子的电子转移解离（ETD）和负离子的质子转移解离（PTD）确定分子结构的生物学重要分子的MALDI-TOF MS-MS的实用技术。这项技术将提供在单次碰撞条件下研究离子-离子碰撞过程的能力，并直接测量电荷转移和碎裂的结果。竞争过程的反应截面将被测量为几种类型的离子-离子碰撞过程。基础研究的重点是导致激发离子的反应，这些离子在碰撞后解离，产生结构信息碎片离子。可通过采用双电荷转移来分析单电荷前体，以首先产生有效碎裂的受激中性粒子，然后通过第二次碰撞使碎片碎裂以产生具有与前体相反的电荷的碎片离子。除了基础知识，这项研究将提供实用的技术，确定单和双电荷的分子离子的分子结构的MALDI产生。该方法应适用于各种各样的分子，包括完整的蛋白质，肽，寡核苷酸，寡糖，糖缀合物，脂质和代谢物，并可以提供速度，灵敏度和特异性的识别和结构的未知，超越了可用的电喷雾电离和离子阱。 该仪器的特点是在最近开发的高性能MALDI-TOF-TOF MS-MS系统中增加了第二个脉冲离子源。来自两个源的脉冲束在碰撞室内合并，其中脉冲在时间上精确同步，并且光束的相对速度精确确定并且非常接近零。所提出的装置将允许敏感的测量相反极性的离子之间的反应和离子和激发中性在低平移能量以前无法访问。反应物的内部温度（或激发）可能相当高，但平移温度非常低，导致这些过程的横截面非常高。约化质量为100 Da、相对速度为1 m/s的碰撞对应的平移能量为5 × 10 -7 eV，平移温度为6 × 10 -3 K。我们不知道任何以前的工作在这些条件下的离子-离子碰撞过程。 公共卫生相关性（由申请人提供）：用于生物应用的质谱分析的“圣杯”是一种提供精确分子量和完整、明确序列的仪器，包括复杂混合物中痕量水平蛋白质的不寻常氨基酸和翻译后修饰。还应提供其他生物学重要分子（包括代谢物、脂质、寡糖、糖缀合物、寡核苷酸和肽）的质量和结构的类似信息。可能就是这里了。

DESCRIPTION (provided by applicant): Merged Beam MALDI TOF-TOF Using Ion-Ion Reactions to Determine Structure of Biological Molecules Summary The ultimate goals of this research are practical techniques for MALDI-TOF MS-MS on biologically significant molecules using electron transfer dissociation (ETD) of positive ions and proton transfer dissociation (PTD) of negative ions to determine molecular structure. This technology will provide the ability to study ion-ion collision processes under single collision conditions with direct measurement of the results in terms of charge transfer and fragmentation. Reaction cross sections for competing processes will be measured for several types of ion-ion collision processes. The emphasis in the fundamental studies is on reactions that lead to excited ions that dissociate following collision to produce structurally informative fragment ions. Singly charged precursors may be analyzed by employing double charge transfer to first produce excited neutrals that fragment efficiently, and then ionize the fragments by a second collision to produce fragment ions with charge opposite that of the precursor. In addition to fundamental knowledge, this research will provide practical techniques for determining molecular structure of singly and doubly charged molecular ions produced by MALDI. The approach should be applicable to a wide variety of molecules including intact proteins, peptides, oligonucleotides, oligosaccharides, glycoconjugates, lipids, and metabolites, and may provide speed, sensitivity, and specificity for identification and structural elucidation of unknowns that surpasses that available with electrospray ionization and ion traps. The instrument features addition of a second pulsed ion source to a recently developed high- performance MALDI-TOF-TOF MS-MS system. Pulsed beams from the two sources are merged within a collision cell with the pulses accurately synchronized in time, and with the relative velocity of the beams accurately determined and very near zero. The proposed apparatus will allow sensitive measurements of reactions between ions of opposite polarity and between ions and excited neutrals at low translational energies not previously accessible. The internal temperature (or excitation) of the reactants may be quite high but the translational temperatures are very low leading to very high cross sections for these processes. Collisions with reduced mass of 100 Da and relative velocity of 1 m/s correspond to translational energy of 5x10-7 eV, and translational temperature of 6x10-3 K. We are not aware of any previous work on ion-ion collision processes under these conditions. PUBLIC HEALTH RELEVANCE (provided by applicant): The "Holy Grail" of mass spectrometry for biological applications is an instrument that provides accurate molecular weight and complete, unambiguous sequence, including unusual amino acids and post- translational modifications, on proteins present at trace levels in complex mixtures. It should also provide similar information on mass and structure of other biologically significant molecules, including metabolites, lipids, oligosaccharides, glycoconjugates, oligonucleotides, and peptides. This may be it.