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首页> 外文期刊>Bulletin of the Chemical Society of Japan >Theoretical Studies on Electronic Structures and Chemical Indices of the Active Site of Oxygenated and Deoxygenated Hemerythrin
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Theoretical Studies on Electronic Structures and Chemical Indices of the Active Site of Oxygenated and Deoxygenated Hemerythrin

机译：氧化和脱氧菊苣素活性部位电子结构和化学指标的理论研究

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摘要

Hemerythrin (Hr) is an oxygen-transport protein that includes a binuclear iron active site, which is found in marine invertebrates. We investigated the origin of the magnetic couplings, the nature of the chemical bond, and the mechanism of the dioxygen binding of Hr using an appropriate theoretical method and realistic models. First, we selected the appropriate functional of DFT; spin-polarized Becke's half and half LYP (UB2LYP) showed reasonably good agreement with the experimental values. Secondly, in order to elucidate the origin of the magnetic couplings and understand the nature of the chemical bond, we estimated a range of chemical indices using natural orbitals obtained at the TJB2LYP level. The results indicate that the origin of the antiferromagnetic coupling for Hr is the σ- and π-type orbital interactions via weak Fe-μO conjugation σ- and π-type superexchange interactions) and that the difference in the strength of the dσ-pσ and dπ-pπ interactions of the diiron core in the active site of Hr is responsible for the difference in the magnetic coupling constants between oxygenated and deoxygenated Hr. Finally, using the Mulliken charge-transfer theory, we analyzed the ionization potentials of molecular oxygen and Hr. We concluded that the dioxygen binding in Hr would proceed via a two-step electron-transfer mechanism.
机译：Hemerythrin（Hr）是一种氧转运蛋白，其中包括在海洋无脊椎动物中发现的双核铁活性位点。我们使用适当的理论方法和现实模型研究了磁耦合的起源，化学键的性质以及Hr的双氧结合机理。首先，我们选择了适当的DFT功能;自旋极化的Becke的一半LYP（UB2LYP）与实验值显示出相当好的一致性。其次，为了阐明磁耦合的起源并了解化学键的性质，我们使用在TJB2LYP水平获得的天然轨道估算了一系列化学指数。结果表明，Hr的反铁磁耦合的起源是通过弱Fe-μO共轭σ和π型超交换相互作用产生的σ和π型轨道相互作用，并且dσ-pσ和在Hr的活性位点中，二铁铁心的dπ-pπ相互作用是造成氧化和脱氧Hr之间磁耦合常数差异的原因。最后，使用Mulliken电荷转移理论，我们分析了分子氧和Hr的电离势。我们得出的结论是，Hr中的双氧结合将通过两步电子转移机制进行。

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