2番目の電子によってシトクロームc酸化酵素の減少は,陽子の転位につながる

Maarten Ruitenberg¹, Aimo Kannt, Ernst Bamberg

¹Department of Biophysical Chemistry, Max-Planck-Institut für Biophysik, Kennedyallee 70, D-60596 Frankfurt/Main, Germany.

Nature

|May 3, 2002

まとめ

サイトクロームc酸化酵素のプロトンポンプは,酸化段階だけでなく,還元期にも発生します. この研究では,陽子ポンプが第2の電子移転で発生し,細胞呼吸機構を明らかにすることを示しています.

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:

サイトクロームc酸化酵素は,細胞呼吸に不可欠であり,酸素を水に還元します.
この酵素によるプロトンポンプはATP合成に不可欠ですが,理解は不十分です.
以前のモデルは,陽子のポンプを酸化段階 (電子の第3/4の移転) とのみ関連付けていた.

研究の目的:

サイトクロームc酸化酵素における陽子ポンプのタイミングとメカニズムを調査する.
陽子ポンプが電子伝送の還元期に発生するかどうかを明らかにする.

主な方法:

膜の電気ポテンシャルを測定する.
酵素の定義された 1 電子の還元状態からスタートします.
制御された電子移転実験.

主要な成果:

サイトクロームc酸化酵素への第2の電子移転は,電荷転移を誘導する.
この電荷転移は,1個の陽子のポンプに相当します.
プロトンポンプは,前回の酸化相とは独立して発生する.

結論:

サイトクロームc酸化酵素によるプロトンポンプは,還元期 (1st/2nd電子移転) で発生することがあります.
この発見は,以前のモデルに異議を唱え,陽子の転位のための改訂されたメカニズムを示唆しています.
この研究は,細胞呼吸のバイオエネルギー学に関する重要な洞察を提供します.

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