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Development of New Molecular Catalysts for Dioxygen Activation and Biomimetic Fuel Cell

用于分子氧活化和仿生燃料电池的新型分子催化剂的开发

基本信息

批准号：
14204073
负责人：
NARUTA Yoshinri
金额：
$ 27.04万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14204073/
关键词：
cytochrome c oxidase copper complex iron porphyrin active site chemical model oxygen activation superoxo complex peroxo complex 複核錯体結晶構造解析酸素活性化反応シトクロムc酸化酵素燃料電池酸素付加反応酸化触媒

项目摘要

Cytochrome c oxidase (CcO) is known to be a family of enzymes, which metabolite dioxygen to water by an efficient four-electron reduction pathway with concomitant translocation of proton through membranes in mitochondria. The enzyme contains heme(hemea_3), (his)_3Cu(Cu_B), and His-cross linked Tyr at the active site. The exact functions, however, of these components as well as its dioxygen reduction mechanism. The enzyme is also interested on the similarity of its reaction with one at the O2 electrode of a fuel cell. Thus, theWe first examined the preparation of heme-Cu complexes and tried to clarify their reactivity with O_2 as well as the structure of the resultant peroxy complexes. Tris(pyridylmethyl)amine-tethered iron porphyrin was reacted with O2 to give the corresponding peroxo complex in a quite high stability. We obtained its single crystals and its X-ray crystallographic analysis showed the peroxo complex taking μ-η^2:η^1 structure. This was the first example of the structura … More l determination of hetero-dimetallic peroxo complexes. Howerver, the peroxo complexes were stable and only showed gradual decomposition to the corresponding μ-oxo one.In order to simulate the dioxygen reaction at the enzyme, the remaining residues, Tyr-His and His as an axial ligand to heme a_3, are considered to be important. We have prepared an elaborate model, which bears all components at the CcO active site. This model exhibited an interesting reaction : First, it gave the corresponding peroxo complex [Fe^<III>-O_2-Cu^<II>], possibly μ-1,2 form, at a low temperature. It was gradually converted to the superoxy one [Fe^<III>-O_2・/Cu^I], where the Cu ion was Cu^I. Since peroxy-to-superoxy transformation has never been reported so far, this is a new reaction. This reaction partly simulates the early stage one of O_2 reaction in the enzyme. Thus, the Tyr group in the Tyr-His crosslink could play an important role for stabilization of the superoxy complex in the enzyme as a H+ donor. The success of the O2 complex at the accurate active site model opens the new way to clarify its further reaction. Less

细胞色素c氧化酶（Cytochrome c oxidase, CcO）是一类酶，它通过一个有效的四电子还原途径将二氧代谢成水，并伴随质子在线粒体膜上的易位。该酶在活性位点含有血红素（hemea_3）、（his）_3Cu（Cu_B）和his交联的Tyr。然而，这些成分的确切功能及其双氧还原机制。这种酶还对它与燃料电池O2电极上的反应的相似性感兴趣。因此，我们首先研究了血红素- cu配合物的制备，并试图澄清它们与O_2的反应性以及所得到的过氧配合物的结构。三（吡啶基甲基）胺系铁卟啉与O2反应，得到相应的过氧配合物，稳定性很高。x射线晶体分析表明，该过氧配合物为μ-η^2:η^1结构。这是结构的第一个例子…更多的测定异双金属过氧配合物。然而，过氧配合物是稳定的，只表现为逐渐分解成相应的μ-氧配合物。为了模拟酶的双氧反应，剩余的残基，tyri -His和His作为血红素a_3的轴向配体，被认为是重要的。我们准备了一个精细的模型，它包含了CcO活性位点的所有成分。该模型显示了一个有趣的反应：首先，它在低温下生成了相应的过氧配合物[Fe^<III>-O_2-Cu^<II>]，可能为μ-1,2形式。它逐渐转化为超氧离子[Fe^<III>-O_2·/Cu^I]，其中Cu离子为Cu^I。由于到目前为止还没有报道过氧到超氧的转化，这是一个新的反应。该反应在一定程度上模拟了酶中O_2反应的早期阶段。因此，Tyr- his交联中的Tyr基团可以作为H+供体在酶的超氧配合物的稳定中发挥重要作用。O2配合物在准确活性位点模型上的成功，为进一步阐明其反应开辟了新的途径。少