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Light-driven Enzymatic Decarboxylation
Published on: May 22, 2016
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基質の歪みは,オロチジン5'-モノフォスファートデカルボキシラーゼの触媒化に寄与する
Masahiro Fujihashi1, Toyokazu Ishida, Shingo Kuroda
1Department of Chemistry, Graduate School of Science, Kyoto University , Sakyo-ku, Kyoto 606-8502, Japan.
Journal of the American Chemical Society
|October 25, 2013
まとめ
オロチジン5'-モノリン酸デカルボキシラーゼ (ODCase) は,キー反応を10^17倍以上加速する. 新しい結晶構造は,ODCaseが基質歪曲と移行状態の安定化を使用して,オロチジン5'-モノフォスファート (OMP) のデカルボキシル化を触媒化する方法を明らかにしています.
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:
- オロチジン5単リン酸デカルボキシラーゼ (ODCase) は,オロチジン5単リン酸 (OMP) からウリジン5単リン酸 (UMP) への本質的なデカルボキシラスを触媒化する.
- ODCaseの正確な反応メカニズムは,特に基質歪曲と移行状態安定化の役割に関する議論の対象であり続けています.
研究 の 目的:
- オロチジン5単リン酸デカルボキシラーゼ (ODCase) の論争の的だった反応機構を解明する.
- ODCase触媒における基質歪みと移行状態安定化の貢献を調査する.
主な方法:
- 8つの新しい結晶構造の取得と分析. ODCaseの複合体とリガンドの類似体.
- 分子ダイナミクスと量子力学/分子力学 (QM/MM) の方法を含む,酵素基板中間物質と電子エネルギーの計算分析.
- 酵素活性部位内のリガンド誘発の構造変化の検討.
主要な成果:
- 結晶構造は,ODCase活性部位内のリガンドアナログ (例えば,6-メチル-UMP,OMPエステル) の重要な歪みを明らかにしました.
- 計算による研究は,酵素基底複合体のカルボキシラート群とピリミジン環の間の結合の歪みを示した.
- この歪みは,活性化自由エネルギー (ΔΔG()) を10-15%減少させることが判明しました.
結論:
- ODCaseは,基質の歪みと,触媒の移行状態の安定化を含む二重戦略を採用しています.
- 酵素の触媒効率は,過渡状態の安定化によって著しく向上し,リシン72 (K72) が主要な役割を果たします.
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