ニトロフォリン4と結合する二元原子リガンドの超高速ダイナミクス
Abdelkrim Benabbas1, Xiong Ye, Minoru Kubo
1Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University, Boston, Massachusetts 02115, USA.
Journal of the American Chemical Society
|February 4, 2010
まとめ
ニトロフォリン4 (NP4) は,酸化窒素 (NO) を鉄化状態と鉄化状態で異なる形で結合する. 鉄性NP4は迅速なNO再結合を示し,鉄性NP4はpH依存のNO放出を示し,その生物学的機能に不可欠である.
科学分野:
- バイオケミストリー バイオケミストリー
- タンパク質のダイナミクス
- 酸化窒素のシグナリング
背景:
- ニトロフォリン4 (NP4) は,酸化窒素 (NO) の貯蔵と放出で知られているヘムタンパク質です.
- その機能は,NOの結合と放出に影響を与えるpHに敏感な形状の変化に依存しています.
- タンパク質は鉄の状態を利用して,低いpHで固くNO結合し,高いpHで放出します.
研究 の 目的:
- NP4.4へのNOと一酸化炭素 (CO) の再結合運動を調査する.
- 鉄の酸化状態と環境のpHがこれらの運動に及ぼす影響を調べる.
- NP4のNO貯蔵および放出機能の背後にあるメカニズムを解明する.
主な方法:
- 超高速運動スペクトル顕微鏡.
- NOとCOのNP4への再結合に関する時間解析研究.
- pHの関数としてのタンパク質構成の変化の分析.
主要な成果:
- 鉄性NP4へのゲミネートNO再結合は迅速 (~7ps) で,pH独立であり,NO放出のための鉄性状態の機能的有用性が限られていることを示唆しています.
- Ferric NP4NOは二相性NO再結合を示し, pH (5〜8) に伴い,相振幅が遅くなり, pH (5〜8) に伴い有意に増加する.
- 鉄性NP4からのNOのオフレートは,pH5から8までの数次数で増加し,タンパク質の"開いた"形状と相関しています.
結論:
- NP4の鉄状は,迅速でpHから独立した再結合により,NOの放出に最適化されていません.
- 鉄性状態のNO放出は,pHに依存する形状の変化,特にヘムポケットの開口によって調節されます.
- NP4のNOを放出する能力は",開かれた"状態の集団と関連する脱出ダイナミクスと直接関連しており,NOの放出におけるその役割を強調しています.
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