XAS AS A NOVEL PROBE OF ELECTRONIC STRUCTURE AND REACTIVITY FOR PROTEIN-BASED SU

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 用硫K边X射线吸收光谱(S K边XAS)作为一种新的探针，研究了硫心自由基在多种多肽/蛋白质体系中的基本反应性，作为一种新的探针来研究这些具有重要生物意义的肽类自由基的电子结构。半胱氨基自由基([CysS？])及其亚砜基衍生物([CysSOn]？)二硫键阴离子自由基([CysS？SCys]1-)被观察到或推测为多种生物学功能的中间体，包括酶催化、远程电子传递、多肽翻译后修饰、细胞氧化还原缓冲，甚至细胞氧化还原信号转导。蛋氨酸自由基([Mets？])被认为参与了神经退行性疾病的通路，如淀粉样蛋白的形成-？斑块。电子顺磁共振是表征自由基物种的主要工具，但硫物种的自旋轨道展宽使这种方法变得复杂。利用硫原子上自由基的性质导致的S 3p？1s前边跃迁，直接探测了这些自由基的电子结构，并研究了氢键和电子离域等因素对这些自由基在不同蛋白质环境中的反应活性的影响。这项工作的一个重要目标是发展S K-EDGE XAS作为一种强大而通用的硫自由基物种探针，以研究广泛的生物体系。

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. The basic reactivity of sulfur-centered radicals is being studied in a variety of peptide/protein systems using Sulfur K-edge X-ray Absorption Spectroscopy (S K-edge XAS) as a novel probe of the electronic structure of these biologically-important peptidic radicals. Cysteinyl radicals ([CysS?]), their sulfoxyl derivatives ([CysSOn]?) disulfide anion radicals ([CysS?SCys]1-) have been observed or postulated as intermediates in several biological functions including enzymatic catalysis, long-range electron transfer, peptide post-translational modification, cellular redox buffering, and even cellular redox signaling. Methionine radicals ([MetS?]) are believed to be involved in neurodegenerative diseases pathways such as the formation of amyloid-? plaques. Electron paramagnetic resonance is the primary tool used for characterization of radical species but this approach is complicated by spin orbit broadening in sulfur species. The S 3p?1s pre-edge transition that results from radical character on a sulfur atom is being used to directly probe the electronic structure of these radicals and to investigate the effect of factors such as hydrogen bonding and electron delocalization on the reactivity of these radicals in various protein environments. An important goal of this effort is to develop S K-edge XAS as a powerful and general probe of sulfur radical species to investigate a wide range of biological systems.