Studies of environmentally relevant molybdenum enzymes

环境相关钼酶的研究

基本信息

批准号：
7683053
负责人：
Russ Hille
金额：
$ 29.79万
依托单位：
UNIVERSITY OF CALIFORNIA RIVERSIDE
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-09-01 至 2011-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7683053
关键词：
Active Sites Amino Acids Arsenates Arsenic Arsenites Behavior Biological Models Catabolism Catalysis Chemicals Chemistry Climate Dimethyl Sulfoxide Drug Metabolic Detoxication Electronics Environment Enzymatic Biochemistry Enzymes Eukaryota Family Goals Hand Health Human Inorganic Sulfates Kinetics Label Metabolic Biotransformation Metals Methodology Molybdenum Nature Oxygen Plants Play Process Property Protocols documentation Raman Spectrum Analysis Reaction Research Personnel Role Site Site-Directed Mutagenesis Sleep Initiation and Maintenance Disorders Source Structure Sulfites Sulfur Unspecified or Sulfate Ion Sulfates Variant Vertebrates Work arsenite oxidase base circular magnetic dichroism computer studies density design dimethyl sulfoxide reductase electronic structure greenhouse gases in vivo member microorganism mutant oxidation prevent programs sulfite oxidase theories

项目摘要

The proposed work focuses on three molybdenum-containing enzymes of environmental relevance: DMSO reductase, arsenite oxidase and sulfite oxidase. The first of these catalyzes the reduction of DMSO to the anti-greenhouse gas DIMS, and as such plays an important role not simply in the global sulfur cycle but in modulating climate as well. The second enzyme catalyzes the oxidation of arsenite to arsenate, an important step in the biotransformation of arsenic in the environment that represents a detoxification mechanism for those microorganisms in which it is found. It is a member of the same family of molybdenum-containing enzymes as DMSO reductase, but has an active site structure that represents a variation on that seen in DMSO reductase. Sulfite oxidase from higher eukaryotes (both vertebrates and plants) catalyzes the final step in sulfur catabolism, the oxidation of sulfite to sulfate, and prevents the deleterioius accumulation of the highly reactive sulfite in vivo. The overall goal of the proposed work is to gain a more complete understanding of the mechanism of action of these enzymes in the context of their structures, comparing and constrasting their behavior. The guiding hypothesis behind the approach is that enzyme function and catalytic power are dictated by the physical and electronic structure of the active site. The Specific Aims include rapid kinetic studies as well as spectroscopic and computational work aimed at determining the electronic structures of the enzyme active sites. In the cases of DMSO reductase and sulfite oxidase, site-directed mutants targetting specific active site amino acid residues will also be examined to evaluate their roles in catalysis.

拟议的工作着重于环境相关性的三种含钼的酶：DMSO 还原酶，砷氧化酶和亚硫酸盐氧化酶。这些第一个催化DMSO降低到抗绿室气体昏暗，因此，不仅在全球硫周期中，而且在也调节气候。第二个酶催化砷的氧化为砷，在代表解毒的环境中生物转化的重要步骤发现的微生物的机制。它是同一家族的成员含钼的酶作为DMSO还原酶，但具有代表A的活性位点结构 DMSO还原酶中发现的变化。来自较高真核生物的亚硫酸盐氧化酶（脊椎动物和植物）催化硫酸盐分解代谢，硫酸盐氧化为硫酸盐的最后一步，并防止高反应性亚硫酸盐在体内的积累。拟议工作的总体目标是在它们的背景下，对这些酶的作用机理有了更完整的了解结构，比较和约束其行为。方法背后的指导假设是酶功能和催化能力取决于活性位点的物理和电子结构。具体目的包括快速的动力学研究以及针对的光谱和计算工作确定酶活性位点的电子结构。在DMSO还原酶和亚硫酸盐氧化酶，靶向特定活性部位氨基酸残基的位置定向突变体也将是检查以评估其在催化中的作用。