XAS OF METALS AND METALLOIDS IN INTRACELLULAR COMPARTMENTS

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。 细胞核、线粒体和空泡系统是包含执行特定功能的蛋白质子集的细胞室。我们建议使用两个系统来确定定位于隔室的金属和类金属的形态。首先，我们建议确定在分离的线粒体中积累的铁的形式。线粒体铁超载是几种神经系统和代谢性疾病的共同特征。目前，人们认为所有过量的线粒体铁都是相同的，但没有结构性证据支持这一观点。铁的积累形式可能取决于被破坏的途径。为了解决这个问题，我们将利用特性良好的酵母铁/硫簇途径。使用XAS，我们建议表征当连接到铁/硫簇组装的特定蛋白质突变时积累的线粒体铁。我们将收集用于指纹识别的铁K边，并在适当的时候检查近边和EXAFS。由于这些酵母基因中的一些与人类有导致特定疾病的同源物，因此对现有物种的明确表征可能会导致“定制铁络合剂”的开发。其次，我们建议确定铜和硒在整个动物和器官中的形态，这些已知的器官可以隔离这些化合物。X射线吸收光谱成像是一种相对较新的技术，已被用于现场探测不同化学物种的空间分布。我们建议将这项技术推广到两个动物模型，即果蝇嗜铜细胞中铜的区域化和水中硒的生物积累。Se和CuXAS谱在亚硒酸盐与亚硒酸盐和CuPrC与CuProus化合物的近边缘最大峰位之间存在约7 eV的差异。这种转变为化学选择性XAS成像提供了充足的对比度。我们的长期目标是将XAS成像应用于哺乳动物系统。

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 nucleus, mitochondria and vacuolar system are cellular compartments containing subsets of proteins that carry out specific functions. We propose to determine the form of metals and metalloids localized to compartments using two systems. First, we propose to determine the form of accumulated iron in isolated mitochondria. Mitochondrial iron overload is a common feature of several neurological and metabolic diseases. Currently, it is assumed that all excess mitochondrial iron is the same but there is no structural evidence to support this view. The form of iron that accumulates may depend on the pathway that is disrupted. To address this issue we will utilize the well-characterized yeast iron/sulfur cluster pathway. Using XAS, we propose to characterize the mitochondrial iron that accumulates when specific proteins, linked to iron/sulfur cluster assembly, are mutated. We will collect iron K-edges for fingerprinting and examine both the near edge and the EXAFS when appropriate. Since some of these yeast genes have human homologues that cause specific diseases, a definitive characterization of the species present could lead to the development of 'custom iron chelators'. Secondly, we propose to determine copper and selenium species in whole animals and organs that are known to sequester these compounds. X-ray absorption spectroscopy imaging is a relatively new technique that has been used to interrogate the spatial distribution of different chemical species in situ. We propose to extend this technique to two animal models, the compartmentalization of copper in the cuprophilic cells of the fruit fly and selenium bioaccumulation in the water boatman. Both Se and Cu XAS spectra, have a difference of about 7eV between the near edge maximal peak positions of selenite vs selenate and cupric vs cuprous compounds. This shift provides ample contrast for chemically selective XAS imaging. Our long-term goal is to apply XAS imaging to mammalian systems.