1型銅の活性部位における超交換経路へのアニゾトロプ的共用性の貢献
Ryan G Hadt1, Serge I Gorelsky, Edward I Solomon
1Department of Chemistry, Stanford University , Stanford, California 94305, United States.
Journal of the American Chemical Society
|October 14, 2014
まとめ
電子伝送タンパク質の銅-硫黄結合の共電性は,効率的な電子伝送のための経路を活性化します. 異なる銅部位タイプは選択的にこれらの経路を利用し,ニートリート還元酵素とマルチ銅酸化酵素における酵素機能を最適化します.
科学分野:
- バイオケミストリー バイオケミストリー
- バイオ・オーガニック化学 バイオ・オーガニック化学
- 酵素触媒は,酵素触媒として作用する.
背景:
- 1型 (T1) 銅部位は,窒素還元酵素 (NiRs) や多銅酸化酵素 (MCOs) などの酵素における電子伝送 (ET) に極めて重要です.
- これらのT1サイトは,システイン-ヒスティジン (Cys-His) ブリッジを通じて触媒センターに接続し,二つの潜在的なET経路 (P1とP2) を提供します.
研究 の 目的:
- T1銅部位の電子構造が分子内電子伝送にどのように影響するかを調査する.
- ET経路の活性化におけるT1銅-硫黄結合共振性の役割を明らかにする.
- 酵素特異的な環境がこれらのET経路を効率的な触媒化のためにどのように調節するかを理解する.
主な方法:
- 電子コップリングおよびスーパー交換メカニズムの計算分析.
- T1銅サイト構造とその対応するET経路のNiRとMCOの比較.
主要な成果:
- T1銅-硫黄結合の高コヴァレンシーは,Cys-Hisブリッジ経由で穴の超交換を活性化します.
- このコヴァレンシー活性電子結合 (HDA) は,P1 (タンパク質骨格) とP2 (H結合) 経路の両方を通して長距離ETを促進します.
- NiRの青 (π型) T1サイトは主にP1を使用し,緑 (σ型) T1サイトはより効率的なP2経路を使用します.
- MCOでは,周囲のタンパク質環境がCys-His経路の形状を変化させ,青いπ位と効率的な触媒のためのHDAを好む.
結論:
- 金属-リガンド結合のアニゾトロピック共用性は,好ましいET経路と電子結合の強さを決定する.
- タンパク質環境は,これらの経路を動的に調節し,最適な酵素機能のためのスーパー交換の選択的活性化を可能にします.
- Cys-HisブリッジはETの汎用的なメディエーターであり,電子結合の調節を通じて異なる触媒要求に適応できます.
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