Zn-His-BkbとZn-His-[Asp/Glu]トライアードのZn-コアの安定性と反応性に対する差異的な影響
Yen-Lin Lin1, Yu-Ming Lee, Carmay Lim
1Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan ROC.
Journal of the American Chemical Society
|August 11, 2005
まとめ
ヒスティジン (His) は亜鉛部位において,構造部位における骨幹カルボニルと,触媒部位におけるカルボキシラートと相互作用する. この研究は,溶媒のアクセシビリティとサイト組成に基づいてこれらの好みを説明し,亜鉛コアの安定性と反応性に影響を与えます.
科学分野:
- バイオケミストリーと分子生物学
- コンピューティング・ケミストリー
- バイオ・オーガニック化学 バイオ・オーガニック化学
背景:
- 亜鉛結合ヒスティジン (His) は,構造的亜鉛部位において,通常,骨幹カルボニルと相互作用する.
- 触媒性亜鉛部位では,Hisは典型的にはアスパルテート/グルタミン酸 (Asp/Glu) 炭酸塩酸と相互作用する.
- この差異的相互作用を左右する要因は完全に理解されていません.
研究 の 目的:
- Zn-bound His.のための第2殻のパートナーの選択を決定する要因を解明する.
- 骨幹カルボニルとAsp/GluカルボキシラートのZn-コアの安定性と反応性に対する貢献を比較する.
主な方法:
- 密度関数理論 (DFT) を採用した体系的な研究.
- 相対的な貢献を評価するための連続体介電計算.
- 溶媒アクセシビリティと Zn-コア組成の分析.
主要な成果:
- 骨幹カルボニルは,構造部位に埋もれたアニオン性Zn-コアを安定させ,Zn-His-Asp/Gluトライアードの欠如を説明します.
- Asp/Gluカルボキシラートは,HOMOエネルギー,OH-反応性,電子転送,および複合体の安定性を高めることによって,触媒性Zn-コアを強化します.
- Asp/Gluカルボキシラートは,His.をプロトン化することで,触媒部位での製品放出を促進する可能性があります.
結論:
- 2次シェルのパートナー選択は,溶媒のアクセシビリティとZn-coreの特性によって決まります.
- 骨幹カルボニルは構造部位で好ましいが,アスプ/グルカルボキシラートは触媒部位で有利である.
- これらの相互作用は,構造的および触媒的亜鉛金属酵素の異なる機能に不可欠です.
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