小分子活性化の内外球PCETメカニズムの切り替え:同じマンガネス複合体からの超酸化変異と酸素/超酸化還元反応性
Isabell Kenkel1, Alicja Franke1, Maximilian Dürr1
1Department of Chemistry and Pharmacy, University Erlangen-Nuremberg , 91058 Erlangen, Germany.
Journal of the American Chemical Society
|January 24, 2017
まとめ
この研究では,水分子が酸化還元酵素の模倣にどのように重要であり,超酸化解離酵素の活動のための陽子結合電子移転を容易にし,酸素と超酸化物の内部圏減少を可能にすることを明らかにしています.
科学分野:
- バイオ有機化学
- 酵素ミミクリ
- 酸化還元酵素の触媒
背景:
- 酵素活性部位の水分は,小分子模倣の研究ではしばしば見過ごされます.
- 酸化還元酵素の作用に関する理解は限られている.
- マンガン複合体 (LOH) は,超酸化物変異酶 (SOD) を模倣し,過酸化水素に反応する.
研究 の 目的:
- マンガンベースのSODミミックの反応性における水交換の役割を調査する.
- 複合体の酸塩,調整,酸化還元特性を決定する.
- SODの活性と二核種への変容のメカニズムを解明する.
主な方法:
- ポテンチオメトリックタイトレーション
- 低温質量スペクトロメトリー
- 17 NMRスペクトロスコーピー (温度と圧力に依存する)
- 電気化学
- ストップフロー運動分析
- 電子パラマグネティック共振 (EPR) スペクトロスコーピー
- 量子化学分析
主要な成果:
- 暫定的に結合した水は,外界のSOD活動のための陽子結合電子移転 (PCET) を促進する.
- 水の欠如は,超酸化物と酸素の内部の減少を可能にします.
- 複合体は二核のMnII種に変容し,ヒドロキシル基とMnIV-オクソ種に対するSOD活性を維持する.
結論:
- 水リンガンドは,マンガン基の超酸化物ディスミュータゼミミカの触媒機構に不可欠である.
- この複合体は,水による協調によって異なる反応性を示し,外球と内球の両方の電子伝達経路を可能にします.
- マンガンの複合体は強固なSOD活動と強力な酸化物質の存在下でのユニークな自己修復機構を示しています.
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