Synthetic Models and Spectroscopy of Nonheme Diiron Enzymes

非血红素二铁酶的合成模型和光谱学

• 批准号: 7363716
• 负责人: LAWRENCE QUE
• 金额: $ 28.37万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7363716
• 关键词: Active Sites; Alkane 1-monooxygenase; Alkanes; Anabolism; Anti-HIV Therapy; Bacteria; Base Sequence; Binding; Biological; Biomimetics; Cell Proliferation; Ceruloplasmin; Class; Complex; Development; Diabetes Mellitus; Dioxygen; Electrochemistry; Electronics; Elongation Factor; Enzymes; Family; Fatty Acid Desaturases; Ferritin; Flavins; Goals; Hemerythrin; Histidine; Invertebrates; Iron; Kinetics; Lead; Ligands; Mammals; Mass Spectrum Analysis; Membrane; Metabolic; Metalloproteins; Methane hydroxylase; Methods; Mixed Function Oxygenases; Modeling; Oxidants; Oxidation-Reduction; Oxidoreductase; Oxygen; Peroxidase; Peroxidases; Peroxides; Pharmaceutical Preparations; Property; Proteins; Range; Research; Ribonucleotide Reductase; Sampling; Site; Spectrum Analysis; Structural Models; Structure; Techniques; Work; X-Ray Crystallography; adduct; carboxylate; complex IV; deoxyhypusine monooxygenase; desaturase; human disease; inositol oxygenase; insight; interest; novel; oxidation; programs; toluene 2-xylene monooxygenase; tumor

DESCRIPTION (provided by applicant): Project Summary. The goal of this proposal is to understand how dioxygen is activated by biological diiron centers in metabolically critical transformations. Nonheme diiron proteins and enzymes perform a variety of essential functions involving dioxygen, including dioxygen transport (hemerythrin), DMA biosynthesis (ribonucleotide reductase), iron storage (ferritin), and oxidations of organic substrates (methane monooxygenase, fatty acid desaturases, alkane and arene hydroxylases, myo-inositol oxygenase, deoxyhypusine hydroxylase). In general, dioxygen activation is proposed to entail a common mechanism involving diiron(lll)-peroxo intermediates and high-valent iron-oxo species derived therefrom. The project goal will be accomplished using a combination of biomimetic and spectroscopic approaches. Building on past accomplishments in modeling structural and spectroscopic properties of such sites, it is proposed to synthesize precursor complexes of tripodal ligands, to react them with O2 or peroxides, and to characterize the metastable intermediates derived therefrom. Of great interest are intermediates such as O2 adducts of diiron(ll) complexes (either iron(ll)iron(lll)-superoxo or diiron(lll)-peroxo species), and species with Fe(lll-)Fe(-IV) and Fe(-IV)Fe(-lV) oxidation states. These complexes will be characterized by X-ray crystallography whenever possible and by a variety of techniques such as NMR, EPR, UV-vis-NIR, Raman, Mossbauer, electrospray mass spectrometry, electrochemistry, and EXAFS. Both stopped-flow and conventional kinetic methods will be used to characterize their mechanisms of formation and decomposition. The oxidative reactivities of these transient complexes towards a range of substrates will be investigated and compared with those of enzyme active sites. Also to be synthesized are complexes that can serve as precedents for the novel oxygen activation mechanism recently proposed for myo-inositol oxygenase entailing an iron(ll)iron(lll) center that binds O2 and a diiron(lll)-superoxo species that acts as the initial oxidant. Parallel to these efforts, our spectroscopic expertise will be applied to elucidating the diiron site structures of methane monooxygenase intermediates and deoxyhypusine hydroxylase. Relevance. Nonheme diiron enzymes perform a variety of metabolically critical functions that require dioxygen activation. Understanding how these enzymes work can lead to the development of new drug strategies for treating some human diseases. For example, myo-inositol oxygenase may be connected to the many complications associated with diabetes mellitus, while deoxyhypusine hydroxylase is required for the formation of mature eukaryotic elongation factor 5a that is essential for cell proliferation and may thus serve as the target for anti-tumor or anti-HIV therapy.

描述（由申请人提供）：项目摘要。该提案的目标是了解双氧在代谢关键转化中如何被生物双铁中心激活。非血红素二铁蛋白和酶执行多种涉及分子氧的基本功能，包括分子氧运输（血红蛋白）、DMA 生物合成（核糖核苷酸还原酶）、铁储存（铁蛋白）和有机底物的氧化（甲烷单加氧酶、脂肪酸去饱和酶、烷烃和芳烃）羟化酶、肌醇加氧酶、脱氧马尿苷羟化酶）。一般而言，分子氧活化被认为需要涉及二铁(III)-过氧中间体和由其衍生的高价铁-氧物种的共同机制。该项目的目标将通过结合仿生和光谱方法来实现。基于过去在模拟此类位点的结构和光谱特性方面取得的成就，建议合成三足配体的前体配合物，使它们与O 2 或过氧化物反应，并表征由此衍生的亚稳态中间体。人们非常感兴趣的是中间体，例如二铁(II)络合物的O2加合物（铁(II)铁(III)-超氧或二铁(III)-过氧物质)，以及具有Fe(III-)Fe(-IV)的物质和 Fe(-IV)Fe(-IV) 氧化态。这些配合物将尽可能通过 X 射线晶体学以及各种技术（例如 NMR、EPR、UV-vis-NIR、拉曼、穆斯堡尔、电喷雾质谱、电化学和 EXAFS）进行表征。停流和传统动力学方法都将用于表征它们的形成和分解机制。将研究这些瞬时复合物对一系列底物的氧化反应性，并与酶活性位点的氧化反应性进行比较。还要合成的复合物可以作为最近提出的肌醇加氧酶的新型氧活化机制的先例，该机制需要结合 O2 的铁（II）铁（III）中心和充当初始氧化剂。与这些努力同时，我们的光谱专业知识将应用于阐明甲烷单加氧酶中间体和脱氧马尿苷羟化酶的二铁位点结构。关联。非血红素二铁酶执行多种需要双氧激活的代谢关键功能。了解这些酶的工作原理可以帮助开发治疗某些人类疾病的新药物策略。例如，肌醇加氧酶可能与糖尿病相关的许多并发症有关，而脱氧马尿苷羟化酶是形成成熟真核延伸因子 5a 所必需的，该因子对于细胞增殖至关重要，因此可以作为抗肿瘤的靶点。或抗艾滋病毒治疗。