リガンド誘発型陽子移転と低障壁水素結合が,X線結晶学によって明らかになった
Derek A Nichols1, Jacqueline C Hargis2, Ruslan Sanishvili3
1†Department of Molecular Medicine, University of South Florida College of Medicine, 12901 Bruce B. Downs Blvd, MDC 3522, Tampa, Florida 33612, United States.
Journal of the American Chemical Society
|June 10, 2015
まとめ
リガンド結合は,CTX-M β-ラクタマゼ内で陽子の移転を誘導し,低バリア水素結合 (LBHBs) を形成することによって,酵素触媒を変化させます. これらの構造は,LBHBsを明らかにします.
科学分野:
- 酵素学と構造生物学について
- 生物物理化学 生物物理化学
背景:
- リンガンド結合は,タンパク質残基のpKa値を調節し,酵素触媒に影響を与える可能性があります.
- 陽子化状態の理解は,酵素機構の解明に不可欠です.
研究 の 目的:
- 超高解像度のX線結晶学を用いてCTX-M β-ラクタマース酵素経路中のプロトネーション状態の変化を視覚化します.
- 低バリア水素結合 (LBHBs) の形成におけるリガンド結合の役割と,その触媒作用への影響を調査する.
主な方法:
- CTX-M β-ラクタマゼの超高解像度 (0.790.84 Å) のX線結晶構造.
- アポ,プレコヴァレンント,およびアシレーショントランジション状態のアナログ複合体の分析.
- 量子力学/分子力学 (QM/MM) 反応経路の計算.
主要な成果:
- リガンド結合時にSer70からGlu166への陽子移転の直接視覚化.
- 準相関複合体におけるSer70とLys73の間の2.53 Åの低バリア水素結合 (LBHB) の観測.
- QM/MMの計算では,陽子伝達障壁が低い (1.53 kcal/mol) と示され,LBHBsが移行状態を安定させることを示唆しています.
結論:
- リガンド誘導による溶解は,酵素活性部位におけるLBHB形成を好む微環境を作り出します.
- LBHBsは,一般的な酸塩触媒における移行状態の安定化に寄与する可能性がある.
- 残留プロトネーション状態の変化は,精密なタンパク質-リガンド相互作用モデリングに不可欠です.
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