プロリルペプチド結合イソメリゼーションのエネルギーに対する溶媒効果
Eric S Eberhardt1, Stewart N Loh, Andrew P Hinck
1Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706.
Journal of the American Chemical Society
|April 1, 2011
まとめ
この研究では,溶媒におけるペプチド結合イソメリゼーションを調査した. 水は,アプロティック溶剤よりも活性化エネルギーを増加させ,タンパク質の折り畳みと機能に影響を与えます.
科学分野:
- バイオケミストリー バイオケミストリー
- 化学物理 化学物理
背景:
- ペプチド結合のイソメリゼーションは,タンパク質の構造と機能にとって極めて重要です.
- ペプチド結合ダイナミクスに対する溶媒の効果を理解することは,タンパク質の行動を予測するために不可欠です.
研究 の 目的:
- モデルペプチド Ac-Gly-[β,δ-(13) C]Pro-OMeを合成し,特徴づけること.
- 様々な溶媒におけるプロリルペプチド結合イソメリゼーションの運動学と熱力学を決定する.
- ペプチド結合イソメリゼーションを調節する際に,水素結合と極性などの溶媒特性の役割を解明する.
主な方法:
- 特別に標識されたペプチドアナログの合成.
- 核磁共振 (NMR) スペクトロスコーピーは,反応運動を研究する.
- 熱力学パラメータを分析するための赤外線 (IR) スペクトロスコピー.
- 9つの異なる溶媒の動きと熱力学的分析.
主要な成果:
- イソメリゼーションの活性化の自由エネルギーは,アプロティック溶剤と比較して水では著しく高かったことが判明しました (1.3 kcal/molの差).
- 極性ではなく,溶媒の水素結合ドナー能力は,活性化エネルギーの観測された変化と相関しています.
- この結果は,イソメリゼーション中の電荷移転を含むアミド共振モデルを支持する.
結論:
- 溶媒の特性,特に水素結合ドーナメントは,ペプチド結合イソメリゼーションのエネルギー学において重要な役割を果たします.
- これらの発見は,ペプチジルプロリルシストランスイソメラーゼ (PPIases) のメカニズムを理解するための意味を持つ.
- ペプチド結合の安定性に対する中程度の影響は,タンパク質の折りたたみ,機能,分解プロセスに影響を与える可能性があります.
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