一度に1つ:ターンオーバーの際に観察された小型のラッカゼにおける分子内電子伝送運動学
Ankur Gupta1, Thijs J Aartsma, Gerard W Canters
1Leiden Institute of Physics, Leiden University , Leiden, The Netherlands.
Journal of the American Chemical Society
|January 31, 2014
まとめ
単一分子酵素学は,Streptomyces coelicolor laccase.で分子内電子伝送 (ET) 率を明らかにしています. これらの速度は,一度に1つの分子で測定され,全体の酵素周回よりも速く,速度を制限していない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
- 酵素の動力学について
- 生物物理化学 生物物理化学とは
背景:
- 単一分子酵素学は,酵素機構の詳細な洞察,特に酸化還元酶における分子内電子移転 (ET) を提供します.
- 内分子ETは,複数のリドックス活性部位を持つ酵素にとって極めて重要です.
研究 の 目的:
- 単一分子レベルで,Streptomyces coelicolor small laccaseの銅センター間の分子内ET率を測定するために.
- 酵素回転中のこれらのET率の分布と特性を調査する.
主な方法:
- 単一分子酵素学を用いて,分子内ETをリアルタイムで監視した.
- 室温とpH7.4.4でラッカースの銅中心間の前後ET率を測定した.
主要な成果:
- 分子内ET率 (前方および後方) は,それぞれ460s−1および85s−1の平均でログノーマル分布に従った.
- アクティベーションエネルギーは347 meV (前方) と390 meV (後方) で,スプレッドは約30 meVと決定されました.
- T1部位縮小の第2次速度定数は,2.9 × 104 M−1 s−1.1 でした.
結論:
- 平均先行分子内ET速度は,酵素の周回率を超えており,これは速度を制限するステップではないことを示唆しています.
- 単一分子測定は,散発方法よりもETダイナミクスのより詳細な理解を提供します.
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