Structure and Mechanism of Myo-Inositol Oxygenase

肌醇加氧酶的结构和机制

基本信息

批准号：
7575616
负责人：
JOSEPH M BOLLINGER
金额：
$ 28.91万
依托单位：
PENNSYLVANIA STATE UNIVERSITY, THE
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-01-15 至 2010-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7575616
关键词：
Address Binding Biochemical Biochemical Reaction Catalysis Cell Nucleus Characteristics Chemicals Chemistry Cleaved cell Complement component C1s Complex Complications of Diabetes Mellitus Copper Coupling Cysteine Data Deuterium Diabetes Mellitus Diagnostic Dissociation Drug Delivery Systems Drug Formulations Electron Nuclear Double Resonance Electrons Enzymes Epitopes Escherichia coli Exhibits Freezing Future Glucuronates Glycols Heme House mice Human Hydrogen Hydrogen Peroxide Hydron Inositol Iron Isotopes Kidney Kinetics Knowledge Label Ligands Light Measurable Measures Metabolic Metals Methane hydroxylase Methods Molecular Monitor Mus Mutagenesis Natural regeneration Nature Nitric Oxide Nuclear Optics Oxidation-Reduction Oxygen Oxygenases Pathology Pathway interactions Pattern Phosphatidylinositols Positioning Attribute Principal Investigator Process Production Property Proteins Publishing Reaction Reducing Agents Relative (related person)Reporting Research Personnel Roentgen Rays Scheme Second Messenger Systems Signal Transduction Site Spectrum Analysis Structure Sulfhydryl Compounds Superoxides Testing Theoretical model Thermodynamics Time Titrations Vertebral column Water X-Ray Crystallography Xylitol Xylulose absorption abstracting adduct analog analytical method chemical bond chemical kinetics cofactor combat density design electronic structure enzyme substrate complex hydroxyl group inhibitor/antagonist inositol oxygenase insight isotope incorporation oxidation pi bond programs research study response second messenger stoichiometry sugar theories three dimensional structure tool trend

项目摘要

DESCRIPTION (provided by applicant): Myo-inositol oxygenase (MIOX) catalyzes the first step in the only known pathway in humans for breakdown of myo-inositol (Ml), the sugar backbone of cell-signaling phosphoinositides. Evidence suggests that increased expression or activity of MIOX may contribute to pathologies commonly associated with diabetes mellitus, marking MIOX as a potential drug target. Our preliminary data show that the MIOX reaction proceeds via an unprecedented chemical mechanism. A non-heme diiron cluster in its mixed-valent, ll/lll, oxidation state, which probably coordinates one or more oxygen atoms of the substrate, reacts with molecular oxygen to generate a formally diiron(lll/lll)-superoxide complex, which abstracts hydrogen from the substrate. We seek to determine by biophysical and biochemical methods: (1) the structure of this unique enzyme and its diiron cofactor; (2) how the protein promotes initial formation and stability of the active, mixed-valent form (which is unstable in many other non-heme diiron proteins); (3) how the substrate interacts with the protein and cofactor; (4) whether and how this interaction activates the cofactor or substrate (or both) for subsequent reaction with O2; and (5) the nature and rate of each chemical step leading from addition of oxygen to the enzyme*substrate complex through release of the product along with the structures of two reactive intermediates that we have already discovered and additional intermediates that remain to be discovered in this sequence. By so doing, we hope to provide the necessary tools for rational design of MIOX inhibitors that could be useful in combating complications from diabetes mellitus.

描述（由申请人提供）：肌醇氧合酶（MIOX）催化人类唯一已知的途径的第一步，即肌醇（ML）损坏，这是细胞信号磷酸固醇的糖骨架。有证据表明，MIOX的表达或活性增加可能有助于通常与糖尿病有关的病理，将Miox标记为潜在的药物靶标。我们的初步数据表明，Miox反应通过前所未有的化学机制进行。在其混合价值的LL/LLL，氧化状态中，非血红素二铁簇可能与底物的一个或多个氧原子配合，与分子氧反应形式上产生一种形式上的二铁（LLL/LLL）-Superoxide-superoxide络合物，从底物中抽象氢气。我们试图通过生物物理和生化方法来确定：（1）这种独特的酶及其二烯辅助因子的结构；（2）蛋白质如何促进活性，混合形式的初始形成和稳定性（在许多其他非血红素二铁蛋白中是不稳定的）；（3）底物如何与蛋白质和辅因子相互作用；（4）这种相互作用是否以及如何激活辅因子或底物（或两者），以使其与O2进行后续反应；（5）从添加氧气到酶*底物复合物的每个化学步骤的性质和速率，以及我们已经发现的两个反应性中间体的结构以及在此序列中待发现的其他中间体的结构。通过这样做，我们希望为Miox抑制剂的合理设计提供必要的工具，这些工具可用于打击糖尿病并发症。