SULFUR SPECIATION IN PLANT LEAVES/LICHENS, AND STUDIES OF METAL-CYS COMPLEXES US

植物叶子/地衣中的硫形态以及金属-CYS 复合物的研究

• 批准号: 7370488
• 负责人: FARIDEH JALILEHVAND
• 金额: $ 0.81万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7370488
• 关键词: SULFUR; SPECIATION; PLANT; LEAVES; LICHENS

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. Sulfur is an essential element for plants, being converted into cysteine and then to other sulfur metabolites. Current research on sulfur metabolism in plants is severely restricted by the present "wet chemistry" methods for identifying sulfur species, which require digestion/heating/destruction of the sample and only provide rather inaccurate "total organic" vs. "total inorganic" amounts of sulfur. By means of sulfur K-edge X-ray absorption spectroscopy (XAS) we will perform detailed speciation analyses of the major sulfur species present in intact plant leaves to clarify the key steps in the sulfur metabolism. We will also study samples from areas in Alberta, Canada, exposed to well-documented extensive sour gas emissions, to investigate the effects on the sulfur metabolism. Lichens, which only take up sulfur from the air, are great natural monitors for sour gas effects. Cysteine and its derivatives are medically used for heavy metal detoxification. Cysteine, one of 21 amino acids found in living organisms, contains three coordinating sites: the amino, thiol and carboxylate groups. The thiol group can form strong bonds and accumulate ions of soft, heavy metals. Coordination chemical studies have so far been focused on metal complexes in the solid state, mostly by elemental analysis, IR and in a few cases, X-ray crystallography. Little is known about the structure and coordination in solution, near to physiological conditions. We will use metal and sulfur XAS to study the local structure around the metal center, i.e. the metal-ligand bond distances, number and type of coordinating atoms, as well as the electronic environment around the sulfur atom in complexes of heavy metals, e.g. Pb, Cd, Hg and Ag, with cysteine and its derivatives.

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心机构，不一定为研究者机构。硫是植物必需的元素，被转化为半胱氨酸，然后转化为其他硫代谢产物。目前对植物中硫代谢的研究受到目前用于鉴定硫物质的“湿化学”方法的严重限制，该方法需要消化/加热/破坏样品，并且仅提供相当不准确的“总有机”与“总无机”硫量。通过硫K边X射线吸收光谱（XAS），我们将进行详细的形态分析的主要硫物种存在于完整的植物叶片，以澄清硫代谢的关键步骤。我们还将研究来自加拿大阿尔伯塔地区的样品，这些样品暴露于有充分记录的广泛的酸性气体排放中，以调查对硫代谢的影响。地衣只从空气中吸收硫，是酸性气体影响的天然监测器。半胱氨酸及其衍生物在医学上用于重金属解毒。半胱氨酸是生物体中发现的21种氨基酸之一，含有三个配位位点：氨基、巯基和羧酸根。巯基可以形成强键并积累软重金属离子。配位化学的研究主要集中在固态的金属配合物上，主要是通过元素分析，IR和在少数情况下，X射线晶体学。在接近生理条件下，对溶液中的结构和配位知之甚少。我们将使用金属和硫XAS研究金属中心周围的局部结构，即金属配体的键距，配位原子的数量和类型，以及重金属，如铅，镉，汞和银，与半胱氨酸及其衍生物的配合物中硫原子周围的电子环境。