構造的適応性 サイトクロームP450におけるヒスティジンヘム結合を促進する
John A McIntosh1, Thomas Heel1, Andrew R Buller1
1Division of Chemistry and Chemical Engineering 210-41, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Journal of the American Chemical Society
|August 25, 2015
まとめ
研究者は重要なシステイン残基をヒスティジンに変異させ,サイトクロームP450 (CYP) 酵素の活性部位を調査した. この構造の変化は,新しい触媒活動と酵素特性を明らかにし,将来の研究に役立てました.
科学分野:
- 生物化学
- 構造生物学
- 酵素学
背景:
- サイトクロームP450 (CYP) 酵素は代謝に不可欠であり,通常は保存されたシステイン残留物を利用してヘム鉄を結合する.
- このシステインの変異は天然のモノオキシゲナーゼの活性を廃止するが,新しいカルベンとニトロンの転移反応を可能にすることができる.
- 新しい触媒機能を設計するには,CYP活性部位の構造を理解することが重要です.
研究 の 目的:
- ヒスティジン結合P450酵素の結晶構造を決定する.
- CYP119における軸性システインの変異による構造的および機能的影響を調査する.
- 合成CYP活性部位の非自然触媒の可能性を調査する.
主な方法:
- Sulfolobus acidocaldariusからの熱安定性CYP119酵素のサイト指向型変異.
- T213A/C317Hの高解像度構造を得るためのX線結晶学.
- 各種の軸性システイン変異体の光譜分析
主要な成果:
- ヒスティジン結合P450 (CYP119 T213A/ C317H) の最初の結晶構造が決定され,ヒスティジンによるヘム鉄の調整が示されました.
- ヒスティジンへの変異は,全体的なタンパク質構造に大きな変化をもたらした.
- 軸性システインは,タンパク質の折りたたみやヘム結合を損なうことなく,他のアミノ酸で置き換えられ,独特のスペクトル特性を有することが判明した.
結論:
- ヒスティジンに結合したP450活性部位は構造的に異なっており,ヘム調整を維持しています.
- 様々なアミノ酸の置換を施したCYP活性部位は安定し,独特の特性を持っています.
- これらの発見は,新しいP450媒介の触媒と反応メカニズムを探求するための基礎を提供します.
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