多核金属酵素活性中心への生物無機化学的アプローチ

多核金属酶活性中心的生物无机化学方法

• 批准号: 06044167
• 负责人: OKAWA Hisashi
• 金额: $ 3.71万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044167/
• 关键词: Metalloenzyme model; Manganese catalase; Hydrogenperoxide; Manganese complex; Multicopper enzyme; Electrontransfer; Functional model; Ascorbate oxidase; 過酸化水素; 不均化反応; 二電子伝達; マンガン(IV)オキソ錯体

1. Model Studies on Manganese Catalase.mu-Phenoxobis (mu-carboxylato) dimanganese (II) core complexes, relevant to a mu-oxobis (mu-carboxylato) dimanganese core supposed for biological manganese catalase (Mn-CAT), have been derived from phenol-based dinucleating ligands and used for model studies on Mn-CAT.They showed a CAT-like activity to decompose H_2O_2 in DMF solution. From detailed studies using these and related complexes, the following important findings were obtained.(1) Based on FAB masspectrometry using isotopic H_2^<18>O_2 and visible spectroscopy showing a characeristic absorption at 530 nm with vibration modes separated by 730 cm^<-1>, an active intermediate {Mn (IV) (=O)}_2 was first detected along with a less reactive intermediate {Mn (II) Mn (IV) (=O)}. On the basis of kinetic considerations, the catalytic cycle by {Mn (IV) (=O)}_2/{Mn (III) (OH)}_2 was proposed.(2) The mu-phenoxobis (mu-carboxylato) dimangenese (II) core structure of the complexes was carefully examin … More ed and it is found the complexes of Cs symmetry give the active cis-{Mn (IV) (=O)}_2 whereas the complexes of C_2 symmetry give the less active {Mn (II) Mn (IV) (=O)}.(3) Dinuclear Mn complexes comprised of elecutronically non-equivalent Mn ions were examined in CAT-like activity. In this case a side eraction through a radical mechanism occurs, giving rise to a reduction in the O_2 yield. The result clearly demonstrates the significance of an equivalent pair of Mn ions in Mn-CAT.(4) Based on studies on CAT-like activity of macrocyclic Mn_2 complexes, the involvement of Mn (III) species was proved. Thus, the cycle of {Mn (IV) (=O)} 2/{Mn (III) (OH)}_2 in the H_2O_2 disproportionation was demonstrated.2. Model Studies on Multi-copper EnzymesA bioinorganic approach was made to the active site of multi-copper enzymes containing type I,type II and type III coppers. An assembly complex comprised of one dinuclear Cu_2 (II,II) and two mononuclear Cu (II) units, {Cu (II) -Cu_2 (II,II)-Cu (II)}, was prepared by the use of a dinucleating ligand derived from the [1 : 2] condensation of 2,6-diformyl-4-methylphenol and tetraethylenepentamine. Electrochemical reduction at the mononuclear center was performed to provide {Cu (I) -Cu_2 (II,II) -Cu (I)}, which caused an intramolecular electron transfer to give {Cu (II) -Cu_2 (I,I) -Cu (II)}. This is the first evidence for the electron transfer supposed for ascorbate oxidase, one of multicopper enzymes. Less

1. Model Studies on Manganese Catalase.mu-Phenoxobis (mu-carboxylato) dimanganese (II) core complexes, relevant to a mu-oxobis (mu-carboxylato) dimanganese core supposed for biological manganese catalase (Mn-CAT), have been derived from phenol-based dinucleating ligands and used for model studies on Mn-CAT.They showed a CAT-like activity to decompose H_2O_2 in DMF solution. From detailed studies using these and related complexes, the following important findings were obtained.(1) Based on FAB masspectrometry using isotopic H_2^<18>O_2 and visible spectroscopy showing a characeristic absorption at 530 nm with vibration modes separated by 730 cm^<-1>, an active intermediate {Mn (IV) (=O)}_2 was first detected along with a less reactive intermediate {Mn (II) Mn (IV) (=O)}. On the basis of kinetic considerations, the catalytic cycle by {Mn (IV) (=O)}_2/{Mn (III) (OH)}_2 was proposed.(2) The mu-phenoxobis (mu-carboxylato) dimangenese (II) core structure of the complexes was carefully examin … More ed and it is found the complexes of Cs symmetry give the active cis-{Mn (IV) (=O)}_2 whereas the complexes of C_2 symmetry give the less active {Mn (II) Mn (IV) (=O)}.(3) Dinuclear Mn complexes comprised of elecutronically non-equivalent Mn ions were examined in CAT-like activity. In this case a side eraction through a radical mechanism occurs, giving rise to a reduction in the O_2 yield. The result clearly demonstrates the significance of an equivalent pair of Mn ions in Mn-CAT.(4) Based on studies on CAT-like activity of macrocyclic Mn_2 complexes, the involvement of Mn (III) species was proved. Thus, the cycle of {Mn (IV) (=O)} 2/{Mn (III) (OH)}_2 in the H_2O_2 disproportionation was demonstrated.2. Model Studies on Multi-copper EnzymesA bioinorganic approach was made to the active site of multi-copper enzymes containing type I,type II and type III coppers. An assembly complex comprised of one dinuclear Cu_2 (II,II) and two mononuclear Cu (II) units, {Cu (II) -Cu_2 (II,II)-Cu (II)}, was prepared by the use of a dinucleating ligand derived from the [1 : 2] condensation of 2,6-diformyl-4-methylphenol and tetraethylenepentamine. Electrochemical reduction at the mononuclear center was performed to provide {Cu (I) -Cu_2 (II,II) -Cu (I)}, which caused an intramolecular electron transfer to give {Cu (II) -Cu_2 (I,I) -Cu (II)}. This is the first evidence for the electron transfer supposed for ascorbate oxidase, one of multicopper enzymes. Less

项目成果

H.Adams: "A dinuclear (mu-Carboxylato) manganese (II) Complex Derived from a Macrocyclic Ligand : A Structural Model for Active Sites in Natural Systems" Angew.Chem.Int.Ed.Engl.34. 2535-2537 (1995)

H.Adams：“源自大环配体的双核（μ-羧基）锰（II）络合物：自然系统中活性位点的结构模型”Angew.Chem.Int.Ed.Engl.34。

M.Ohba,N.Maruono,H.Okawa,T.Enoki and J.-M.Latour: "A new Bimetallic Ferromagnet with a Rare Rope-Ladder Structure" J.Am.Chem.Soc.116. 11566-11567 (1994)

M.Ohba、N.Maruono、H.Okawa、T.Enoki 和 J.-M.Latour：“一种具有罕见绳梯结构的新型双金属铁磁体”J.Am.Chem.Soc.116。

K.motoda: "Isomerization of a Linear Pentamine, 1,4,7,10,13-Pentaazatridecane, to a Branched Form, 4- (Ainoethyl) 1,4,7,10-tetraazadecane, on a Schiff-base Copper Complex RElevant to Multi-copper Enzymes" Chem.Lett.1065-1066 (1995)

K.motoda：“在希夫碱铜配合物上，线性五胺 1,4,7,10,13-五氮杂十三烷异构化为支链形式 4-(氨基乙基)1,4,7,10-四氮杂十烷

C.Higuchi,H.Sakiyama,R.Isobe,H.Okawa and D.E.Fenton: "Dinuclear Mn(II)Complexes of Unsymmetrical Phenol-based Ligand:Synthesis,Structure and Catalase-like Activity" J.Chem.Soc.Dalton Trans.1009-1103 (1994)

C.Higuchi、H.Sakiyama、R.Isobe、H.Okawa 和 D.E.Fenton：“不对称苯酚基配体的双核 Mn(II) 配合物：合成、结构和过氧化氢酶样活性” J.Chem.Soc.Dalton Trans

C.Higuchi: "Dinuclear Manganese(II)Complexes of Unsymmetrical Phenol-based Dinucleating Ligands with Amino and Imino Chelating Arms.Synthesis,Structure and Catalase-like Activity" J.Chem.Soc.Dalton Trans.1097-1103 (1995)

C.Higuchi：“具有氨基和亚氨基螯合臂的不对称苯酚基双核配体的双核锰 (II) 复合物。合成、结构和过氧化氢酶样活性”J.Chem.Soc.Dalton Trans.1097-1103 (1995)