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酪氨酸酶是一种能氧化酪氨酸残基为对苯醌的生物活性酶,其活性部位含有双铜核心并参与氧化还原反应。实验证明这两个铜核心易与氧气结合生成两种异构体μ~-η~2:η~2-Cu_2O_2(Ⅱ)和bis(μ-oxo)-Cu_2O_2(Ⅲ),且它们具有不同的电子结构和化学性质。用量子化学密度泛函理论对乙(撑)二胺和乙腈配合的μ~-η~2:η~2-Cu_2O_2(Ⅱ)和bis(μ-oxo)-Cu_2O_2(Ⅲ)进行了理论研究,结果表明该两种异构体能量差别较小,相互转化的势垒较低。μ~-η~2:η~2-Cu_2O_2(Ⅱ)中的Cu—O主要是离子键,Cu_2O_2呈“Z”构型,而bis(μ-oxo)-Cu_2O_2(Ⅲ)中的Cu—O主要是共价键,Cu_2O_2呈“V”构型,在氧化还原反应中具有更强的亲电子能力。
Tyrosinase is a bioactive enzyme that oxidizes tyrosine residues to p-benzoquinone. Its active site contains double copper core and is involved in the redox reaction. Experiments show that the two copper cores are easy to combine with oxygen to form two kinds of isomers μ ~ -η ~ 2: η ~ 2-Cu_2O_2 (Ⅱ) and bis (μ-oxo) -Cu_2O_2 Electronic structure and chemical properties. The theoretical studies of μ ~ -η ~ 2 ~ η ~ 2-Cu_2O_2 and bis-μ-oxo-Cu_2O_2 complexes with ethylenediamine and acetonitrile by quantum chemical density functional theory The results show that the energy difference between the two isomers is relatively small, and the barrier between each other is relatively low. Cu-O in μ ~ -η ~ 2: η ~ 2-Cu_2O_2 (Ⅱ) is mainly ionic bond, Cu_2O_2 is in “Z ” configuration, -O is mainly covalent bond, Cu 2 O 2 is in “V” configuration and has stronger electrophilic ability in redox reaction.