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水溶液中のペプチドエノラートの形成と安定性
Ana Rios1, John P Richard, Tina L Amyes
1Department of Chemistry, University at Buffalo, SUNY, Buffalo, New York 14260-3000, USA.
Journal of the American Chemical Society
|July 11, 2002
まとめ
この研究では,ペプチドN-terminiのデプロトン化率を定量化し,内部残留物よりも有意に反応性が高いことを明らかにしました. この違いは,ペプチドとタンパク質の化学を理解する上で極めて重要です.
科学分野:
- バイオ物理化学 バイオ物理化学
- 化学動力学 化学動力学
- 有機化学 オーガニック・ケミストリー
背景:
- ペプチドとタンパク質の安定性は,それらの端末群の反応性によって影響を受けます.
- アルファアミノ炭素のデプロトネーション運動を理解することは,化学的振る舞いを予測するために不可欠です.
研究 の 目的:
- D2Oにおける様々な炭素酸のデプロトン化のための第2次速度定数を決定する.
- H2O中のヒドロキシドイオンへの陽子の移転率を推定する.
- ペプチドにおけるアルファアミノおよびアルファカルボニル炭素の酸性に影響を与える要因を調査する.
主な方法:
- 速度定数を決定するためにデュテオキシドイオン (D2O) を使用した運動測定.
- H2Oにおける水酸化イオン速度常数の推定.
- 線形相関分析 log k ((HO) と炭素酸 pKa.
主要な成果:
- 二次速度定数 (k ((DO)) は,N端および内部アルファ-アミノ炭素,およびN-アセチル化ペプチドにおけるアセチルメチルおよびアルファ-アミノ炭素のデプロトン化のために決定されました.
- これらの炭素酸の推定pKa値は23.9から30.8.8の範囲にある.
- 陽子化されたN端のアルファアミノ炭素は,内部残留物よりも約130倍反応性があります.
結論:
- N端アルファ-アミノ群の反応性の向上は,カチオニンアルファ-カルボニル炭酸のデプロトネーションのための下部マルカス固有障壁に起因する.
- 電子取り除く強さの違いにもかかわらず,カチオンのNH3+と中性なNHAcグループは,アルファ-カルボニル炭酸のpKaを同様に減少させます.
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