含氮硫多牙基之ㄧ價銅和二價銅錯合物的合成、結構與藍銅蛋白活性中心之相關研究
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2007
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Abstract
藍銅蛋白具有電子傳遞的功能，其活性中心的二價銅離子配位兩個His和一個Cys形成一個三角平面，與軸位上配位的Met成為扭曲的四面體結構。本研究以兩個含氮硫三牙基BBMeMS、BBMeES為主要配子，分別合成了二價銅錯合物[Cu(BBMeMS)(CH3CN)2(H2O)](ClO4)2 (1)、[Cu(BBMeES)(CH3CN)(η1-ClO4)](ClO4) (2)作為起始物，再將二價銅錯合物1、2分別與一系列不同的硫化物反應以模擬藍銅蛋白的活性中心。若在室溫下反應，可分別得到無色的一價銅錯合物[Cu(η2-BBMeMS)- (CH3CN)](ClO4) (7)、[Cu(CH3CN)(μ-BBMeES)Cu(BBMeES)](ClO4)2 (8)；然而，若在-78℃下反應，可產生深藍色的產物。當二價銅錯合物1與Sodium diethyldithiocarbamate反應，可以分離得到diethyldithiocarbamate配位的二價銅錯合物[Cu(BBMeMS)((C2H5)2NCS2)](ClO4)2 (3)以及一價銅錯合物7。我們也嚐試模擬還原態的藍銅蛋白活性中心，將一價銅錯合物8分別加入去質子化的硫化物thiobenzoate以及2-(trimethylsilyl)benzene- thiolate，並且藉由核磁共振光譜的鑑定，推測有錯合物[Cu(BBMeES)- (C6H5COS-)]與[Cu(BBMeES)((CH3)3SiC6H4S-)]的生成。
此外，我們也合成了兩個雙牙基的配子: 1-methyl-2-(methylthio- methyl)-1H-benzimidazole (MMB)、Sodium (1-methylbenzimidazol-2-yl)- methanethiolate (L2)來嘗試模擬藍銅蛋白的活性中心，過程中得到了已發表的二價銅錯合物[(η2-MMB)2Cu(η1-ClO4)](ClO4) (6)以及一價銅錯合物[(η2-MMB)(η1-MMB)Cu](ClO4) (9)。
本研究的結果發現，以電中性的含氮硫雙牙或三牙基所合成的二價銅化合物與去質子化的硫化物反應時，銅金屬中心容易被還原成ㄧ價銅離子。如何設計的可穩定二價銅中心的適當配位基將是合成藍銅蛋白擬態分子的成功關鍵。
The active site of the well known electron transferase blue copper protein, has a distorded tetrahedral geometry, which the Cu ion is coordinated to two histidine and one cysteine in an approximately trignoal plane and to a methionine at the axial position. In this study, we have synthesized the Cu(II) complexes, [Cu(BBMeMS)(CH3CN)2(H2O)](ClO4)2 (1) and [Cu(BBMeES)(CH3CN)(η1-ClO4)](ClO4) (2) by the reaction of Cu(ClO4)2•6H2O with the N2S(thioether) ligands, BBMeMS and BBMeES, respectively, to be the precursor to prepare synthetic mimics for the active site of the blue copper protein. As Cu(II) complexe 1 and 2 reacted with a series of thiolate ligands, colorless Cu(I) complexes, [Cu(η2-BBMeMS)- (CH3CN)](ClO4) (7) and [Cu(CH3CN)(μ-BBMeES)Cu(BBMeES)](ClO4)2 (8) were obtained at room temperature; whereas, a deep blue solution was observed at - 78℃. When Cu(II) complex 1 reacted with sodium diethyldit- hiocarbamate, a diethyldithiocarbamate coordinated Cu(II) complex [Cu- (BBMeMS)((C2H5)2NCS2)](ClO4)2 (3) and a Cu(I) complex 7 were isolated. We have also attempted to model the active site of the reduced form of blue copper protein by reacting complex 8 with thiobenzoate and 2-(trimethylsilyl)benzenethiolate , respectively. From NMR analysis of the products, two Cu(I)-thiolate complex [Cu(BBMeES)(C6H5COS-)] and [Cu(BBMeES)((CH3)3SiC6H4S-)] were expected. In addition, we have prepared two bidentate ligand: 1-methyl-2-(methy- lthiomethyl)-1H-benzimidazole (MMB) and Sodium(1-methylbenzimidazol- 2-yl)methanethiolate (L2) for modeling the active site of blue copper protein. We have obtained a Cu(II) complex [(η2-MMB)2Cu(η1-ClO4)](ClO4) (6) and a Cu(I) complex [(η2-MMB)(η1-MMB)Cu](ClO4) (9). In summary, we found that the thiolate ligands have a very high tendence to reduce a Cu(II) ion which were coordinated to the neutral bidentate or tridentate N/S ligands. It is very crucial to design an appropriate ligand, which can stabilized a Cu(II) ion, to mimic the coordination environment of the active site of blue copper protein.
The active site of the well known electron transferase blue copper protein, has a distorded tetrahedral geometry, which the Cu ion is coordinated to two histidine and one cysteine in an approximately trignoal plane and to a methionine at the axial position. In this study, we have synthesized the Cu(II) complexes, [Cu(BBMeMS)(CH3CN)2(H2O)](ClO4)2 (1) and [Cu(BBMeES)(CH3CN)(η1-ClO4)](ClO4) (2) by the reaction of Cu(ClO4)2•6H2O with the N2S(thioether) ligands, BBMeMS and BBMeES, respectively, to be the precursor to prepare synthetic mimics for the active site of the blue copper protein. As Cu(II) complexe 1 and 2 reacted with a series of thiolate ligands, colorless Cu(I) complexes, [Cu(η2-BBMeMS)- (CH3CN)](ClO4) (7) and [Cu(CH3CN)(μ-BBMeES)Cu(BBMeES)](ClO4)2 (8) were obtained at room temperature; whereas, a deep blue solution was observed at - 78℃. When Cu(II) complex 1 reacted with sodium diethyldit- hiocarbamate, a diethyldithiocarbamate coordinated Cu(II) complex [Cu- (BBMeMS)((C2H5)2NCS2)](ClO4)2 (3) and a Cu(I) complex 7 were isolated. We have also attempted to model the active site of the reduced form of blue copper protein by reacting complex 8 with thiobenzoate and 2-(trimethylsilyl)benzenethiolate , respectively. From NMR analysis of the products, two Cu(I)-thiolate complex [Cu(BBMeES)(C6H5COS-)] and [Cu(BBMeES)((CH3)3SiC6H4S-)] were expected. In addition, we have prepared two bidentate ligand: 1-methyl-2-(methy- lthiomethyl)-1H-benzimidazole (MMB) and Sodium(1-methylbenzimidazol- 2-yl)methanethiolate (L2) for modeling the active site of blue copper protein. We have obtained a Cu(II) complex [(η2-MMB)2Cu(η1-ClO4)](ClO4) (6) and a Cu(I) complex [(η2-MMB)(η1-MMB)Cu](ClO4) (9). In summary, we found that the thiolate ligands have a very high tendence to reduce a Cu(II) ion which were coordinated to the neutral bidentate or tridentate N/S ligands. It is very crucial to design an appropriate ligand, which can stabilized a Cu(II) ion, to mimic the coordination environment of the active site of blue copper protein.
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藍銅蛋白, blue copper protein