Role of Tyrosine Residue in Methane Activation at the Dicopper Site of Particulate Methane Monooxygenase: A Density Functional Theory Study

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• 作者：Yoshihito Shiota ; Gergely Juh谩sz ; Kazunari Yoshizawa
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：July 15, 2013
• 年：2013
• 卷：52
• 期：14
• 页码：7907-7917
• 全文大小：496K
• 年卷期：v.52,no.14(July 15, 2013)
• ISSN：1520-510X

文摘

Methane hydroxylation at the dinuclear copper site of particulate methane monooxygenase (pMMO) is studied by using density functional theory calculations. The electronic, structural, and reactivity properties of a possible dinuclear copper species (渭-oxo)(渭-hydroxo)Cu^IICu^III are discussed with respect to the C鈥揌 bond activation of methane. We propose that the tyrosine residue in the second coordination sphere of the dicopper site donates an H atom to the 渭-畏²:畏²-peroxoCu^IICu^II species and the resultant (渭-oxo)(渭-hydroxo)Cu^IICu^III species can hydroxylate methane. This species for methane hydroxylation is more favorable in reactivity than the bis(渭-oxo)Cu^IIICu^III species. The H-atom transfer or proton-coupled electron transfer from the tyrosine residue can reasonably induce the O鈥揙 bond dissociation of the 渭-畏²:畏²-peroxoCu^IICu^II species to form the reactive (渭-oxo)(渭-hydroxo)Cu^IICu^III species, which is expected to be an active species for the conversion of methane to methanol at the dicopper site of pMMO. The rate-determining step for the methane hydroxylation is the C鈥揌 cleavage, which is in good agreement with experimental KIE values reported so far.