酵素活性部位におけるX線およびNMR結晶学:トリプトファン合成酵素におけるインドリンキノノイド中間体
Jinfeng Lai1, Dimitri Niks, Yachong Wang
1Department of Chemistry, University of California, Riverside, California 92521, USA.
Journal of the American Chemical Society
|December 15, 2010
まとめ
固体NMRとX線結晶学を組み合わせると,トリプトファン合成酵素の重要な中間物質の詳細な構造が明らかになる. このアプローチは,触媒処理中のプロトネーション状態を定義することによって,酵素機構を明確にします.
科学分野:
- バイオケミストリー バイオケミストリー
- 構造生物学 構造生物学とは
- 酵素触媒は,酵素触媒として作用する.
背景:
- 酵素の仕組みを理解するには,プロトネーションやハイブリッド化状態などの詳細な化学情報が必要です.
- X線結晶学だけでは,高解像度でも,これらの微細な化学的詳細を解明するのに苦労することが多い.
- 核磁共振 (NMR) スペクトロスコピーの化学的シフトは,地元の化学環境に対して非常に敏感です.
研究 の 目的:
- 活性触媒処理中のピリドクサル-5'-リン酸塩依存型トリプトファン合成酵素におけるインドリンキノイド中間物質の化学的に豊富な結晶構造を決定する.
- 詳細な構造分析のためのX線結晶学と固体状態NMRスペクトロスコピーの組み合わせの力を示します.
主な方法:
- X線結晶学と固体NMRスペクトルスコピーを組み合わせたシナギスティックなアプローチを採用しました.
- アブ・イニシオ計算化学を用いた反応基板アナログの最適化モデル.
- 最適化中に結晶学的に決定された座標で固定されたサイドチェーン残基.
- 基板上の特定の位置での化学的シフトを測定するために, (13) C と (15) N のラベルを使用しました.
主要な成果:
- インドリンキノノイド中間物の化学的に詳細な構造を成功裏に決定した.
- サブストラットと触媒残留の電荷とプロトネーション状態の様々なモデルを区別する.
- 特定のラベルされた位置に計算された化学的シフトの重要な影響を特定しました.
結論:
- 組み合わせたNMRと結晶学のアプローチは,化学的に詳細な3次元構造を提供します.
- この研究は,基質のタウトメリック形態の間の均衡を強調しています.
- メジャータウトメア形態のプロトネーション状態は,その後の触媒的ステップを指示する上で極めて重要です.
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