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的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 研究中心，而研究中心不一定是研究者所在的机构。 硫为中心的自由基的基本反应性正在研究在各种肽/蛋白质系统中使用硫K-边X射线吸收光谱（S K-边XAS）作为这些生物重要的肽自由基的电子结构的新探针。半胱氨酰自由基（[CysS？]），它们的亚砜基衍生物（[CysSOn]？）二硫阴离子自由基（[CysS？SCys]1-）已被观察到或假定为若干生物功能中的中间体，包括酶催化、远程电子转移、肽翻译后修饰、细胞氧化还原缓冲、甚至细胞氧化还原信号传导。甲硫基（[MetS？]）被认为与神经退行性疾病途径有关，例如淀粉样蛋白的形成-？斑块电子顺磁共振是用于表征自由基物质的主要工具，但这种方法由于硫物质中的自旋轨道加宽而变得复杂。S 3P？硫原子上的自由基特征导致的1 s前边缘跃迁被用来直接探测这些自由基的电子结构，并研究诸如氢键和电子离域等因素对这些自由基在各种蛋白质环境中的反应性的影响。这项工作的一个重要目标是发展S K边XAS作为一个强大的和一般的探针硫自由基物种调查范围广泛的生物系统。

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.