トライオセフォスファートイソメラーゼによる触媒におけるループクランプサイドチェーンの役割
Xiang Zhai1, Tina L Amyes1, John P Richard1
1Department of Chemistry, University at Buffalo, SUNY , Buffalo, New York 14260-3000, United States.
Journal of the American Chemical Society
|November 17, 2015
まとめ
トリオフォスファートイソメラーゼ (TIM) の変異は酵素触媒に影響する. ほとんどの変異は基質結合と移行状態を同様に変化させ,一部の変異は触媒部位の反応性に影響する.
科学分野:
- 生物化学
- 酵素運動
- タンパク質工学
背景:
- トリオフォスファートイソメラーゼ (TIM) は,酵素基板複合体を水素結合で安定させる.
- TIMのループ7の特定の残留物 (Y208,S211) はループ6と相互作用する.
- これらの相互作用を理解することは 酵素の機能と工学の鍵です
研究 の 目的:
- Y208とS211の変異がTIMの運動パラメータに与える影響を調査する.
- これらの変異が移行状態の安定化にどのように影響するかを分析する.
- 基板結合エネルギーと触媒効率の関係を解明する.
主な方法:
- Y208とS211でTIMのサイト指向型変異.
- 全基板 (DHAP,GAP) と基板片 (グリコアルデヒド,フォスフィートダイアニオン) の運動パラメータの測定
- 動的データの線形対数相関分析
主要な成果:
- ほとんどのTIM変異は,完全な基板と基板の断片の活性化バリアに類似した変化を引き起こした.
- 触媒速度 (kcat) と移行状態結合エネルギー (Kd) の間には相関関係が見られた.
- Y208変異は主にダイアニオン結合エネルギーを減少させ,Y208Fは触媒部位に影響を与えました.
結論:
- TIM変異は通常,移行状態の安定化に均等に影響する.
- 酵素基板結合エネルギーは,ミカエリス複合体と移行状態の間で分割されます.
- 特定の変異は,単純な結合エネルギー効果を超えて,触媒部位の反応性を変化させることができる.
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