Possible Peroxo State of the Dicopper Site of Particulate Methane Monooxygenase from Combined Quantum Mechanics and Molecular Mechanics Calculations.
Possible Peroxo State of the Dicopper Site of Particulate Methane Monooxygenase from Combined Quantum Mechanics and Molecular Mechanics Calculations.
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DOI：
10.1021/acs.inorgchem.5b02603
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发表时间：
2016-02
影响因子：
4.6
通讯作者：
Shuhei Itoyama;Kazuki Doitomi;T. Kamachi;Y. Shiota;K. Yoshizawa
中科院分区：
文献类型：
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作者：
Shuhei Itoyama;Kazuki Doitomi;T. Kamachi;Y. Shiota;K. Yoshizawa
甲烷单加氧酶（pMMO）是甲烷营养细菌中不可或缺的膜金属酶，提出了在pMMO的双核铜位点上有效发生甲烷羟化酶。在Rosenzweig等人报道的pMMO静息态x射线晶体结构的基础上，采用量子力学和分子力学相结合的计算方法，讨论了pMMO的铜活性位点的静息态和可能的过氧态。二铜位点具有独特的结构，其中一个铜由两个组氨酸咪唑配位，另一个铜由一个组氨酸咪唑和一个n端组氨酸伯胺螯合。根据B3LYP-D/TZVP理论计算得出的Cu-Cu距离为2.62 Å， diccopper位点的静息态可归属于混合价Cu(I)Cu（II）态。利用静息态结构和双氧水，合理地得到了与血青素和酪氨酸酶相似的μ-η(2):η(2)-过氧化物- cu (II)2结构。在开壳层单重态下，Cu-Cu和O-O的距离分别为3.63和1.46 Å。并与血青素、酪氨酸酶和人工合成的双铜模型化合物的结构特征进行了比较。利用TD-DFT计算并分析了μ-η(2):η(2)-过氧化物- cu (II)2态的光学特征。
Enzymatic methane hydroxylation is proposed to efficiently occur at the dinuclear copper site of particulate methane monooxygenase (pMMO), which is an integral membrane metalloenzyme in methanotrophic bacteria. The resting state and a possible peroxo state of the dicopper active site of pMMO are discussed by using combined quantum mechanics and molecular mechanics calculations on the basis of reported X-ray crystal structures of the resting state of pMMO by Rosenzweig and co-workers. The dicopper site has a unique structure, in which one copper is coordinated by two histidine imidazoles and another is chelated by a histidine imidazole and primary amine of an N-terminal histidine. The resting state of the dicopper site is assignable to the mixed-valent Cu(I)Cu(II) state from a computed Cu-Cu distance of 2.62 Å from calculations at the B3LYP-D/TZVP level of theory. A μ-η(2):η(2)-peroxo-Cu(II)2 structure similar to those of hemocyanin and tyrosinase is reasonably obtained by using the resting state structure and dioxygen. Computed Cu-Cu and O-O distances are 3.63 and 1.46 Å, respectively, in the open-shell singlet state. Structural features of the dicopper peroxo species of pMMO are compared with those of hemocyanin and tyrosinase and synthetic dicopper model compounds. Optical features of the μ-η(2):η(2)-peroxo-Cu(II)2 state are calculated and analyzed with TD-DFT calculations.