Tyrosinase and catechol oxidase activity of copper(I) complexes supported by imidazole-based ligands: structure–reactivity correlations

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• 作者：Franziska Wendt ; Christian Näther…
• 刊名：Journal of Biological Inorganic Chemistry
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：21
• 期：5-6
• 页码：777-792
• 全文大小：2,454 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Biochemistry
  Microbiology
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-1327
• 卷排序：21

文摘

Four new imidazole-based ligands, 4-((1H-imidazol-4-yl)methyl)-2-phenyl-4,5-dihydrooxyzole (L_OL1), 4-((1H-imidazol-4-yl)methyl)-2-(tert-butyl)-4,5-dihydrooxyzole (L_OL2), 4-((1H-imidazol-4-yl)methyl)-2-methyl-4,5-dihydrooxyzole (L_OL3), and N-(2,2-dimethylpropylidene)-2-(1-trityl-1H-imidazol-4-yl-)ethyl amine (L_imz1), have been synthesized. The corresponding copper(I) complexes [Cu(I)(L_OL1)(CH₃CN)]PF₆ (CuL_OL1), [Cu(I)(L_OL2)(CH₃CN)]PF₆ (CuL_OL2), [Cu(I)(L_OL3)(CH₃CN)]PF₆ (CuL_OL3), [Cu(I)(L_imz1)(CH₃CN)₂]PF₆ (CuL_imz1) as well as the Cu(I) complex derived from the known ligand bis(1-methylimidazol-2-yl)methane (BIMZ), [Cu(I)(BIMZ)(CH₃CN)]PF₆ (CuBIMZ), are screened as catalysts for the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC-H₂) to 3,5-di-tert-butylquinone (3,5-DTBQ). The primary reaction product of these oxidations is 3,5-di-tert-butylsemiquinone (3,5-DTBSQ) which slowly converts to 3,5-DTBQ. Saturation kinetic studies reveal a trend of catalytic activity in the order CuL_OL3 ≈ CuL_OL1 > CuBIMZ > CuL_OL2 > CuL_imz1. Additionally, the catalytic activity of the copper(I) complexes towards the oxygenation of monophenols is investigated. As substrates 2,4-di-tert-butylphenol (2,4-DTBP-H), 3-tert-butylphenol (3-TBP-H), 4-methoxyphenol (4-MeOP-H), N-acetyl-l-tyrosine ethyl ester monohydrate (NATEE) and 8-hydroxyquinoline are employed. The oxygenation products are identified and characterized with the help of UV/Vis and NMR spectroscopy, mass spectrometry, and fluorescence measurements. Whereas the copper complexes with ligands containing combinations of imidazole and imine functions or two imidazole units (CuL_imz1 and CuBIMZ) are found to exhibit catalytic tyrosinase activity, the systems with ligands containing oxazoline just mediate a stoichiometric conversion. Correlations between the structures of the complexes and their reactivities are discussed.KeywordsType 3 copper enzymesTyrosinaseCatechol oxidaseKineticsDioxygen activation