サイトクロームc酸化酵素によるプロトンポンプのメカニズム原理

Kristina Faxén¹, Gwen Gilderson, Pia Adelroth

¹Department of Biochemistry and Biophysics, The Arrhenius Laboratories for Natural Sciences, Stockholm University, SE-106 91 Stockholm, Sweden.

Nature

|September 9, 2005

まとめ

サイトクロームc酸化酵素 (CytcO) のプロトンポンプの分子機構が解明されました. 陽子ポンプは,触媒部位で酸素への陽子の移転と結合し,内部電子移転ではありません.

科学分野:

バイオケミストリーバイオケミストリー
分子生物学は分子生物学である.
バイオエネルギー学バイオエネルギー学

背景:

エアロビックな生物の細胞呼吸は,酸素への電子移転のために膜に結合したタンパク質複合体を利用する.
このプロセスは,ATP合成に不可欠なトランスメブラン電気化学プロトンのグラデントを生成します.
サイトクロームc酸化酵素 (CytcO) は末端酵素複合体であり,O2をH2Oに還元し,陽子を膜にポンプします.

研究の目的:

CytcOにおける電子移転によって推進される陽子ポンプの分子機構を決定する.
酸素還元時にCytcOがタンパク質を膜に移動させる方法を解明する.

主な方法:

この研究では,CytcO.O.における電子移転と陽子の転位の間のメカニズム的なカップリングを調査した.
焦点は,酸素が水に還元される触媒部位に置かれました.

主要な成果:

CytcOのプロトンポンプは,触媒部位でO2へのプロトン転送と機械的に結合しています.
このカップリングは,複合体内の内部電子伝送イベントとリンクされるのではなく,発生します.

結論:

この発見は,酸化還元誘導型陽子ポンプの動作に関する新しい原理を示唆している.
このメカニズムは,CytcOによる陽子の転位のための可能な分子経路に重大な制約を課します.

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