酵素構造:基質誘導による構成変化による活性オロチジン5'-モノホスファットデカルボキシラーゼの形成
Archie C Reyes1, 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
|October 24, 2017
まとめ
オロチジン5'-モノフォスファートデカルボキシラーゼ (OMPDC) は,基板誘導による構造変化によって移行状態を安定させる. この酵素メカニズムは,基板の断片を巻き込み,酵素活性化につながる可能性があります.
科学分野:
- 生物化学
- 酵素運動
- 構造生物学
背景:
- オロチジン5エクストクォーテスシングル・モノフォスファートデカルボキシラーゼ (OMPDC) は,ピリミジン生物合成における重要な酵素である.
- 酵素のメカニズム,特に移行状態の安定化を理解することは,薬の開発に不可欠です.
研究 の 目的:
- 移行状態の安定化に焦点を当てて,OMPDCの触媒メカニズムを調査する.
- サブストラット結合と酵素構成の変化の役割を解明する.
主な方法:
- OMPDCとその基質5 - フロロロート (FO) を用いた酵素運動の研究
- 運動パラメータ (kcat/Km) と移行状態の安定化エネルギーの分析
- 基板断片 (フォスフォディアニオン,リボシル,オロタート環) と効果体 (フォスフィートダイニオン,d-グリセロール3酸化物,d-エリトリトール4酸化物) の安定化貢献を調査した.
主要な成果:
- OMPDCは,OMPの脱炭素化のための移行状態を31 kcal/molで安定させる.
- 安定化への特定の貢献は,フォスフォディアニオン (11. 8 kcal/mol),リボシル環 (10. 6 kcal/mol),およびオロタート環 (8. 6 kcal/mol) について定量化された.
- FO脱炭素化の移行状態は, phosphite dianion,d-glycerol 3-phosphate,およびd-erythritol 4-phosphateによってそれぞれ5. 2,7. 2および9. 0kcal/molで安定化される.
- 基板断片の結合は酵素の構造変化を誘導し,ケージ複合体を形成する.
結論:
- OMPDCは,転移状態を安定化するために,基板誘発型変化を触媒として利用する.
- 基板断片の結合相互作用は,オロタート環を触媒的に適した形状に固定するために重要である.
- 酵素活性化は,これらの基質誘発型変化の結果である可能性があります.
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