トリプトファンライアゼ (NosL): 5'-デオキシアデノシルラジカル媒介型変異の角
Dhananjay M Bhandari1, Dmytro Fedoseyenko1, Tadhg P Begley1
1Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
Journal of the American Chemical Society
|December 22, 2016
まとめ
ラジカルS-アデノシル-l-メチオニン (SAM) 酵素NosLは,多用途の化学反応を示しています. 5'-デオキシアデノシル基は水素原子を抽象化し,二重結合を加え,トリプトファンライアスの新しい反応経路を明らかにする.
科学分野:
- 生物化学
- 酵素学
- 有機化学
背景:
- トリプトファンリアゼ (NosL) は,S-アデノシル-l-メチオニン (SAM) 酵素である.
- L-トリプトファンから3-メチル-2-インドール酸の形成を触媒化する.
研究 の 目的:
- NosL触媒反応における5-デオキシアデノシル基の化学的多様性を調査する.
- 改造されたトリプトファン基板と活性サイト成分とのNosLの反応性を調査する.
主な方法:
- サイト・ディレクテッド・ミュータジェネシス (NosL Y90A)
- 改造されたトリプトファン類 (Nα-cyclopropyltryptophan,ケトン,アルケーン類) の使用
- ディチオニットを使った 過激な捕獲実験
主要な成果:
- Nα-cyclopropyltryptophan から水素原子の抽出は,アミノ基ではなく,Cα位置で発生する.
- 基質アミンをケトンまたはアルケーンに置き換えると,水素原子抽出から二重結合添加への反応経路が変化する.
- 5 -デオキシアデノシル基は, [4Fe-4S] クラスタに追加することができます.
- ディチオナイトは 活性サイトラジカルを 効果的に閉じ込めます
結論:
- 5デオキシアデノシル基は,これまで理解されていたよりも広範な化学反応性を持っています.
- NosLのメカニズムは,基質の改変に適応する複雑な基質化学を含んでいます.
- これらのラジカル経路の理解は,新しい酵素反応の設計に情報を与えることができます.
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