Following Heme Oxygenase Reaction at Atomic Scale

原子尺度的血红素加氧酶反应

• 批准号: 14380300
• 负责人: SAITO Masao
• 金额: $ 7.74万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14380300/
• 关键词: Heme; heme oxygenase; X-ray crystallography; Reaction mechanism; oxygen activation

Heme oxygenase (HO) oxidatively degrades heme to biliverdin. Specific aim of this research project is to delineate the molecular mechanism of the enzyme action through determination of the high resolution crystal structures of all the catalytically significant reaction intermediates. We have chosen HmuO, a heme oxygenase of Corynebacterium diphtheriae, the spectroscopic and enzymatic properties of which have been extensively studied by our research team.In the first year, we determined the crystal structures of ferric and ferrous forms of the heme complex of HmuO, the initial and the second steps of the heme degradation at 1.4 and 1.5 Å resolution. We have found that protons required for HO catalysis is channeled from the solvent water to the oxygen activation site through different conduit between mammalian HO and HmuO despite the high similarity in the overall protein fold between these two HO proteins.In the second year, we have successfully obtained the crystals of the catalytically critical oxy form and determined its structure at 1.85 A resolution. Due to low stability of the oxy form, previous crystallization attempts of oxy HO by other investigators had not been successful, and our publication is the first report of the structure of the catalytically significant oxy form. The structure has resolved long standing important questions on HO, including why oxygen affinity of heme oxygenase is very high, how heme oxygenase prevents product inhibition, and which parts of the active site are relevant to regio-selective hydroxylation of the heme group.The crystal structures of the HmuO complexes with the final product (biliverdin) and its immediate precursor (iron biliverin) have also been solved. These structures provide clues to understand the mechanism of the substrate release from the HO protein, the rate limiting step of the HO catalysis.

血红素氧化酶（HO）氧化降解血红素为双脂蛋白。该研究项目的具体目的是通过确定所有催化有效反应中间体的高分辨率晶体结构来描述酶作用的分子机制。我们选择了HMUO，这是二甲甲虫的血红素加氧酶，我们的研究团队已通过研究团队进行了广泛研究的光谱和酶学特性。我们确定了heme heme heme shemuo的晶体结构，最初是heme heme semulos and and and and and and and and and and and and and and and and 1.4的晶体结构。我们发现，HO催化所需的蛋白质通过哺乳动物HO和HMUO之间的不同导管传播到氧气激活位点，尽管这两个HO蛋白之间的总体蛋白质折叠率很高，第二年，我们已经成功地获得了催化氧气的晶体，并确定了其在1.85的结构。由于氧气形式的稳定性较低，其他研究者先前对氧气的结晶尝试并未成功，我们的出版是第一个报告催化显着的氧气形式的结构。该结构已经解决了关于HO的长期重要问题，包括为什么血红素氧酶的氧亲和力很高，血红素氧化酶如何阻止产品抑制，以及活性位点的哪些部分与血红素组的调节羟基化有关。血红素组的羟基化。这些结构提供了了解从HO蛋白（HO催化的速率限制步骤）的底物释放机理的线索。

项目成果

Tomita, et al.: "Recent progress in biochemical studies of hemoprotein"Seikagaku. 75(7). 577-587 (2003)

富田等人：“血红素蛋白生化研究的最新进展”Seikagaku。

Denisov et al.: "Cryogenic absorption spectra of hydroperoxo-ferric heme oxygenase, the active intermediate of enzymatic heme oxygenation"FEBS Lett.. 532(1-2). 203-206 (2002)

Denisov 等人：“氢过氧铁血红素加氧酶的低温吸收光谱，酶促血红素加氧的活性中间体”FEBS Lett.. 532(1-2)。

Davydov et al.: "Kinetic isotope effects on the rate-limiting step of heme oxygenase catalysis indicate concerted proton transfer/heme hydroxylation"J.Am.Chem.Soc.. 125(52). 16208-16209 (2003)

Davydov 等人：“动力学同位素对血红素加氧酶催化限速步骤的影响表明协同质子转移/血红素羟基化”J.Am.Chem.Soc.. 125(52)。

Coyle, et al.: "FeNO structure in distal pocket mutants of myoglobin from resonance Raman spectroscopy"Biochemistry. 42(17). 4896-4903 (2003)

Coyle 等人：“来自共振拉曼光谱的肌红蛋白远端口袋突变体中的 FeNO 结构”生物化学。

Unno et al.: "Crystal Structure of the Dioxygen-bound Heme Oxygenase from Corynebacterium diphtheriae : IMPLICATIONS FOR HEME OXYGENASE FUNCTION"J.Biol.Chem.. 279(20). 21055-21061 (2004)

Unno等人：“来自白喉棒状杆菌的双氧结合血红素加氧酶的晶体结构：对血红素加氧酶功能的影响”J.Biol.Chem.. 279(20)。