還元的に活性化された酸化窒素還元酵素は,基板と直接反応する

Jeannine M Chan¹, John A Bollinger, Cassidy L Grewell

¹Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA.

Journal of the American Chemical Society

|March 12, 2004

まとめ

酸化窒素還元酵素は,そのCuZセンターでN2OをN2に変換する. この研究は,活性化酵素がN2Oを結合し,潜在的触媒中間状態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
微生物学微生物学とは
酵素学酵素学とは

背景:

バクテリアによる脱窒化は,窒素酸化物を,酸化窒素還元酵素 (N2OR) が最終的なN2OからN2への変換を触媒として変換します.
酵素の活性部位であるミュ4硫化物橋渡し型四核CuZセンターは,この反応に不可欠です.

研究の目的:

アクロモバクター・サイクロクラストからのN2ORの基板相互作用と触媒機構を調査する.
活性化酵素内のCuZセンターの酸化状態を特徴付ける.

主な方法:

還元的に活性化されたN2ORの分離と特徴づけ.
可視吸収および電子パラマグネティック共振 (EPR) スペクトロスコーピー.
15Nラベル付N2Oを用いた酵素アッセイ.

主要な成果:

メチルバイオゲンによる還元活性化により,N2ORの特異活性が15倍まで増加した.
スペクトル解析により,CuZの中心が [4Cu(I) ] の酸化状態に達することが確認されました.
N2Oの添加とラベル付き製品の検出の際のスペクトル変化は,基板相互作用と潜在的な触媒中間物質を示唆しています.

結論:

活性化されたN2ORはN2Oと結合し,安定状態の周回に先立つ基板相互作用のステップを示唆しています.
970nmでの新しい吸収帯は,N2O還元における重要な触媒中間物質を意味する可能性があります.

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