ニトリオキシドの再結合とニトリオキシド脱出のダイナミクスは,ホースラディッシュペロキシダースに含まれています
Xiong Ye1, Anchi Yu, Paul M Champion
1Department of Physics and Center for Interdisciplinary Research on Complex System, Northeastern University, Boston, Massachusetts 02115, USA.
Journal of the American Chemical Society
|February 2, 2006
まとめ
この研究では,酸化窒素 (NO) がホーレンラディッシュ過酸化酵素 (HRP) に再結合する超高速な動力学が報告されています. ミオグルビンとは異なり,HRPは単純な指数関数的なNO再結合を示し,溶媒がヘムポケットに直接アクセスすることを示しています.
科学分野:
- バイオケミストリー バイオケミストリー
- 化学動力学 化学動力学
- 酵素学 酵素学とは
背景:
- 酸化窒素 (NO) は,生物学的システムにおいて重要な役割を果たします.
- ヘムタンパク質のNO連帯ダイナミクスを理解することは極めて重要です.
- ホーラーラディッシュペロキシダゼ (HRP) は,ヘム義肢群の重要な酵素である.
研究 の 目的:
- NOのHRPへの再結合の超高速運動性を初めて調査する.
- HRPとミオグロビン (Mb) の NO 再結合ダイナミクスを比較する.
- ベンゾヒドロキサミック酸 (BHA) がHRPから脱出するNOリガンドの脱出率に及ぼす影響を決定する.
主な方法:
- 超高速の運動測定.
- 時間解像度スペクトルスコピー.
- ジェミナート再結合とリガンド脱出運動の分析.
主要な成果:
- NOからHRPへの再結合のゲミナート運動は,鉄分と鉄質の両方にとって指数関数的です.
- Ferric HRPは,NOのゲミナート再結合時間常数15-30psを示しています.
- 鉄製HRPは時間常数約7psを示しています.
- HRPからのNOリガンド脱出率は,BHAの存在に大きく依存しています.
- HRPは,Mb.とは異なり,ディスタルヘムポケットへの直接的な溶媒アクセスを示しています.
結論:
- HRPにおける単純な指数的なNO再結合は,ヘムリラクゼーションがMbで観察された非指数的な再結合の源ではないことを示唆しています.
- NOの脱出率に対するBHAの劇的な影響は,Hemeポケットへのリガンドのアクセスを調節する役割を示しています.
- これらの発見は,NO結合に関するHRPとMbの構造的および動的差異についての洞察を提供します.
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