Transient Intermediates in Electron and Proton Transfer

电子和质子转移中的瞬态中间体

• 批准号: 0750048
• 负责人: Frantisek Turecek
• 金额: $ 40.62万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0750048&HistoricalAwards=false
• 关键词: Transient; Intermediates; Electron; Proton; Transfer

With the support of an award from the Organic and Macromolecular Chemistry Program, Professor Franticek Turecek will address highly reactive molecules, radicals, and cation-radical intermediates that are produced by electron transfer to and deprotonation of cations derived from polar molecules such as peptides, nucleosides, and transition metal complexes. The knowledge gained from the proposed studies will be used to explain the reactivity of transient species relevant to electron-ion and ion-ion recombination processes in biomolecules of current interest and to formulate specific and general mechanisms governing the stability and unimolecular dissociations of a variety of highly reactive and elusive species. The proposed studies of reactive intermediates will employ experimental methods allowing for femtosecond collisional electron transfer in beam experiments, as well as electron capture in isolated ions trapped in electrostatic and magnetic fields. Special model compounds will be synthesized to separate intramolecular interactions by restricting the peptide ion conformational space. Fixed-charge groups will be used to control the energetics of electron attachment and transfer and thus to affect the electronic state(s) that are accessed by ion-electron recombination and collisional electron transfer. Ab initio computational methods will be employed to provide relative, dissociation, and transition state energies to be used for RRKM calculations of unimolecular dissociation and isomerization rate constants. Intellectual meritThe proposed research addresses fundamental and hitherto unresolved questions regarding the dissociations of peptide radicals and cation-radicals. Experiments are proposed that will permit the study of unimolecular dissociations of these transient species on a range of short time scales and under conditions of electron attachment and femtosecond collisional transfer. Electron structure theory calculations are an integral part of the proposed research in both experiment planning and data interpretation.Broader impactsPeptide radicals and cation-radicals have been of considerable interest due to their role as intermediates in mass spectrometric analytical methods for peptide sequencing and detection of protein post-translational modifications. Applications of these methods extend to biology, medicine, and other life sciences, and have been fueled by the availability of commercial instruments for electron capture dissociation and electron transfer dissociation. However, fundamental understanding of the chemistry of transient peptide cation-radicals is essential for the rational use of electron-based methods for peptide and protein sequencing. Studies of ion discharge and immobilization on metal-oxide surfaces have already brought practical results in procedures for the manufacturing of special surfaces for medical implants and selective mass spectrometric detection of phosphopeptides. The proposed research in this area is aimed at gaining insight into the processes leading to biomolecule discharge and immobilization on surfaces.

在有机和大分子化学计划的奖项的支持下，Franticek Turecek教授将解决高活性分子，自由基和阳离子-自由基中间体，这些中间体是通过电子转移和来自极性分子（如肽，核苷和过渡金属络合物）的阳离子的去质子化产生的。从拟议的研究中获得的知识将被用来解释相关的电子-离子和离子-离子重组过程中的生物分子的当前利益的瞬态物种的反应性，并制定具体和一般的机制，管理的稳定性和单分子解离的各种高活性和难以捉摸的物种。拟议的活性中间体的研究将采用实验方法，允许飞秒碰撞电子转移束实验，以及电子捕获孤立的离子被困在静电场和磁场。 通过限制肽离子的构象空间，合成特殊的模型化合物来分离分子内的相互作用。固定电荷基团将用于控制电子附着和转移的能量学，从而影响通过离子-电子复合和碰撞电子转移获得的电子状态。将采用从头计算方法来提供用于RRKM计算单分子解离和异构化速率常数的相对、解离和过渡态能量。 智力meritThe拟议的研究解决了基本的和迄今尚未解决的问题，肽自由基和阳离子自由基的解离。实验提出，将允许这些瞬态物种的单分子解离的研究范围内的短时间尺度和条件下的电子附着和飞秒碰撞转移。电子结构理论计算是一个不可分割的一部分，在实验规划和数据interpretation.Broader impactsPeptide自由基和阳离子自由基已相当大的兴趣，由于其作为中间体在质谱分析方法肽测序和蛋白质翻译后修饰检测的作用。这些方法的应用扩展到生物学、医学和其他生命科学，并且已经被用于电子捕获解离和电子转移解离的商业仪器的可用性所推动。然而，对瞬时肽阳离子自由基化学的基本理解对于合理使用基于电子的方法进行肽和蛋白质测序是必不可少的。对金属氧化物表面的离子放电和固定化的研究已经在制造用于医疗植入物的特殊表面和磷酸肽的选择性质谱检测的过程中取得了实际成果。这一领域的拟议研究旨在深入了解导致生物分子放电和固定在表面上的过程。