Mg2+はチミジラート合成酵素の表面に結合し,内部活性部位の水素移転に影響を与えます
Zhen Wang1, Paul J Sapienza, Thelma Abeysinghe
1Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
Journal of the American Chemical Society
|April 25, 2013
まとめ
マグネシウムイオン (Mg2+) は,チミジラート合成酵素 (TSase) の表面に結合し,その構造を安定させ,DNA合成を7倍加速します. この長距離相互作用は酵素の活性に影響を与え,新しい薬剤の設計を導く.
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
- 構造生物学 構造生物学とは
背景:
- Thymidylate synthase (TSase) は,DNA合成に不可欠であり,薬剤の主要標的である.
- TSase活性に対するマグネシウムイオン (Mg2+) の影響は知られていますが,その背後にあるメカニズムは不明です.
研究 の 目的:
- Mg2+がEscherichia coli TSaseの活性と相互作用し,その活性を調節するメカニズムを解明する.
- Mg2+結合とTSase機能への影響に関する構造的および運動的証拠を提供するため.
主な方法:
- X線結晶学を用いて,結合Mg2+を有するTSaseの構造を決定した.
- 酵素動力学と核磁共鳴 (NMR) のリラクゼーション実験は,Mg2+がTSaseの活性と動力学に及ぼす影響を分析するために実施されました.
主要な成果:
- Mg2+は,葉酸共因子のグルタミル部分の近くにあるE. coli TSaseの外部に結合し,そのような結合の最初の構造的証拠を示しています.
- Mg2+結合は,閉じた三元酵素複合体を安定させ,活性化エントロピーを減らし,約7倍にヒドリド移転を加速します.
- 動的同位体効果は変わらず,Mg2+がヒドリド移転ステップを変化させるのではなく,基質の近接性のためにタンパク質の動きを促進することを示す.
結論:
- Mg2+は,長距離の表面相互作用を通じてTSaseの活性を調節し,タンパク質のダイナミクスと酵素動態に影響を与えます.
- TSaseのMg2+調節を理解することは,細菌のTSase相互作用を標的とした種特有の抗葉酸抗生物質の設計のための洞察を提供します.
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