Structure and Mechanism of Myo-Inositol Oxygenase

肌醇加氧酶的结构和机制

• 批准号: 7201907
• 负责人: JOSEPH M BOLLINGER
• 金额: $ 28.24万
• 依托单位: PENNSYLVANIA STATE UNIVERSITY, THE
• 依托单位国家: 美国
• 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/7201907
• 关键词: Address; Binding; Biochemical; Biochemical Reaction; Catalysis; Cell Nucleus; Characteristics; Chemicals; Chemistry; Cleaved cell; Complement component C1s; Complex; Complications of Diabetes Mellitus; Condition; Copper; Coupling; Cysteine; Data; Deuterium; Diabetes Mellitus; Diagnostic; Dissociation; Drug Delivery Systems; Drug Formulations; Electron Nuclear Double Resonance; Electronics; Electrons; Enzymes; Epitopes; Escherichia coli; Exhibits; Freezing; Future; Glucuronates; Glycol; 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; Object Attachment; Optics; Oxidation-Reduction; Oxygen; Oxygenases; Pathology; Pathway interactions; Pattern; Phosphatidylinositols; Positioning Attribute; Principal Investigator; Process; Production; Property; Proteins; Publishing; Rate; 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; concept; density; design; enzyme substrate complex; glucuronate; hydroxyl group; inhibitor/antagonist; inositol oxygenase; insight; isotope incorporation; oxidation; programs; research study; response; second messenger; stoichiometry; sugar; theories; three dimensional structure; tool; trend

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）：肌醇加氧酶（MIOX）催化人类中唯一已知的肌醇（MI）分解途径的第一步，肌醇（MI）是细胞信号磷酸肌醇的糖骨架。有证据表明，MIOX的表达或活性增加可能导致通常与糖尿病相关的病理，这标志着MIOX是潜在的药物靶点。我们的初步数据表明，MIOX反应通过一种前所未有的化学机制进行。处于其混合价II/III氧化态的非血红素二铁簇（其可能与底物的一个或多个氧原子配位）与分子氧反应以生成形式上的二铁（III/III）-超氧化物络合物，其从底物中提取氢。我们试图通过生物物理和生物化学方法确定：（1）这种独特的酶及其二铁辅因子的结构;（2）蛋白质如何促进活性混合价形式的初始形成和稳定性（其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）用于随后与O2的反应;和（5）从向酶添加氧开始的每个化学步骤的性质和速率 * 底物复合物通过释放产物沿着我们已经发现的两种活性中间体的结构和在该序列中仍待发现的另外的中间体。通过这样做，我们希望为合理设计MIOX抑制剂提供必要的工具，这些抑制剂可用于对抗糖尿病并发症。