DNA光解酵素の光活性化中にタンパク質内原素移転

C Aubert¹, M H Vos, P Mathis

¹Section de Bioénergétique (CNRS URA 2096), CEA Saclay, Gif-sur-Yvette, France.

Nature

|June 13, 2000

まとめ

酵素におけるラジカル転送は議論されている. この研究は,DNA光解酵素における電子の移転が陽子の移転に先行し,急性反応のメカニズムを明らかに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
酵素学酵素学とは
スペクトル顕微鏡検査です.

背景:

アミノ酸ラジカルは,酵素反応に不可欠です.
リボヌクレオチド還元酵素のように,タンパク質における長距離の根幹移転は,メカニズム的に議論されている.
メカニズムには,電子の移転に続いて陽子の放出,または協調したH原子の移転が含まれます.

研究の目的:

Escherichia coliのDNA光解酵素の光活性化メカニズムを調査するために.
ラジカル拡散における電子と陽子の移転イベントのシーケンスを解明する.
酵素的急性反応における電子移転とH原子移転のメカニズムを区別する.

主な方法:

フォトアクティベーションを研究するために時間解像度吸収スペクトルスコピーを用いた.
ラジカル形成と転移の動態は,光誘導後に監視された.
電子と陽子の移転イベントのタイミングを決定するために,運動分析が行われました.

主要な成果:

興奮したフラビンアデニンジヌクレオチド (FAD) 基は,トリプトファンの電子を30psi以内に抽象化します.
その後の電子移転は,3つのトリプトファンの鎖に沿って発生します.
末端のトリプトファンカチオンラジカルは,約300nsで溶媒に陽子を放出し,電子の移転が陽子の解離に先行することを確認します.

結論:

この研究は,DNA光解酶における連続的な電子移転に続いて,陽子の解離メカニズムが続くことを実証しています.
この発見は,酵素における長距離の急性移転メカニズムに関する重要な洞察を提供します.
同様のメカニズムは,他のフォトリアーゼのような青光受容体でも動作する可能性があります.

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