Met471Cysチラミンβ-モノオキシゲナーゼのヒドロキシラーゼ活性について
Corinna R Hess1, Zinian Wu, Adora Ng
1Department of Chemistry, University of California, Berkeley, California 94720-3220, USA.
Journal of the American Chemical Society
|August 20, 2008
まとめ
チラミンβ-モノオキシゲナーゼ (TbetaM) のメチオニンの銅結合部位における変異を調査した. Met471Cysの変異体は,独特の酵素活性を維持し,酸化酸素活性化におけるメチオニンの役割を強調した.
科学分野:
- バイオケミストリー バイオケミストリー
- 酵素の動力学について
- バイオ・オーガニック化学
背景:
- チラミンβ-モノオキシゲナーゼ (TbetaM) は,水酸化反応に不可欠な銅モノオキシゲナーゼである.
- Cu (M) 部位にあるメチオニン残留物 (Met471) は,ダイオキシゲンの活性化と触媒化に不可欠であると考えられている.
- このメチオニンの役割を理解することは,銅モノオキシゲナーゼ機構の解明の鍵です.
研究 の 目的:
- TbetaM機能におけるMet471残留物の役割を調査する.
- 銅結合と酵素活性に対するMet471における突然変異の影響を調査する.
- 新型TbetaM変異体,Met471Asp,Met471Cys,およびMet471His.を特徴づけるために
主な方法:
- サイト・ダイレクト・ミュータゲネシスにより,Met471Asp,Met471Cys,Met471His TbetaMの変種が生成される.
- 銅の結合と協調幾何学を評価するために,EPRスペクトロスコーピーを含むスペクトロスコーピ分析を行います.
- 酵素活性アッセイは,チラミンの基質水酸化を測定する.
主要な成果:
- 3つの変異体とも,野生型のTbetaM.に比較可能な銅結合親和性を示した.
- EPRスペクトロスコーピーは,変異体と野生型の酵素で同一のCu (II) 調整幾何学を示した.
- Met471Cys変異体のみが基板ヒドロキシル化活性を示し,Cu(M) 部位で最初の活性変異体でした.
結論:
- Met471Cys変異体は,変化したCu(M) サイトリガンドを持つTbetaM変異体の最初の機能的な例を提供します.
- この結果は,TbetaM.の触媒機構におけるメチオニン残基の重要な役割を強調しています.
- システインのユニークな活性性は,銅中心による酸化酸素活性化に関するバイオミメティック研究におけるシステインの潜在的関連性を強調しています.
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