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ミトコンドリアのアミドキシム還元分子の酸化窒素還元におけるオキシルとヒドロキシルラジカル移転

Jing Yang¹, Logan J Giles¹, Christian Ruppelt²

¹†Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States.

Journal of the American Chemical Society

|April 22, 2015

まとめ

ミトコンドリアアミドキシム還元成分 (mARC) 酵素は,電子パラ磁気共振 (EPR) と計算を使用して,窒素還元を研究しています. 窒素酸塩が陽子化されると,障壁のない経路が明らかになり,電子の移転を容易にします.

科学分野:

バイオケミストリーバイオケミストリー
酵素学酵素学とは
コンピューティング・ケミストリー

背景:

ミトコンドリアアミドキシム還元成分 (mARC) は,酸化還元反応に関与するモリブデンを含む酵素です.
mARCの触媒メカニズム,特にニートリートとの相互作用を理解することは,細胞呼吸経路の解明に不可欠です.

研究の目的:

mARC酵素によるナトリートの1電子還元反応の座標を調査する.
触媒機構における酵素結合モリブデンと基板プロトネーションの役割を明らかにする.

主な方法:

複合電子パラマグネティック共振 (EPR) スペクトロスコピーは,パラマグネティックな種を検出する.
断片軌道分析を含む計算的アプローチで,反応経路とバリアをモデル化します.

主要な成果:

パラマグネティックなMo(V) 種は,減少したmARCとニートリートの反応によって生成されます.
EPRの高精度パラメータは,mARCとスルフィート酸化酵素との類似性を示しています.
2つの還元メカニズムが評価されました:プロトン化されていない窒素酸塩のための控えめなバリア (14 kcal / mol) とプロトン化窒素酸塩のための無障壁経路.

結論:

モリブデンの中心に近接するニトリートのプロトネーションは,障壁のない触媒変換を可能にします.
高Mo-O (H) -N-O共相性は,π軌道経路経由で電子の移転を容易にする.
特定された軌道上の制約と触媒機構は,mARCおよび他のパイラノプテリン・モリブデン酵素に関連しています.

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