一个水分子稳定了加化氨酸zwitterion
Matthew F Bush1, James S Prell, Richard J Saykally
1Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA.
Journal of the American Chemical Society
|October 13, 2007
概括
将单个水分子添加到化氨酸离子中会稳定zwitterionic形式,影响其结构. 金属离子的大小也会影响这些水合氨基酸集群中的协调.
科学领域:
- 物理化学 物理化学
- 计算化学的计算化学
- 频谱学是一种光谱学.
背景情况:
- 研究氨基酸在溶液中的行为对于理解生物过程至关重要.
- 氨基酸的zwitterionic性质是它们化学性质和相互作用的基础.
- 溶解效应,特别是水合,可以显著改变生物分子的稳定性和结构.
研究的目的:
- 研究单个水分子水化对化氨酸,化氨酸和化氨酸甲基集群的结构和能量效应.
- 为了确定金属离子 (与) 和水解对阿尔金因的zwitterionic状态的影响.
- 为了阐明金属离子在化氨酸集群中的协调偏好 (NO与OO).
主要方法:
- 红外动作光谱学被用来探测离子星团的振动频率和结构.
- 计算化学,特别是B3LYP/6-31++G**计算,用于建模能量和结构.
- 将实验光谱与计算结构进行比较,以确定稳定的配置.
主要成果:
- 单一水合的化氨酸表现出对 25-32 kJ/mol 稳定的体体形式的偏好,与其非体体不溶性对应物不同.
- 水合化和化的试验光谱显示了相似之处,表明了质子化侧链,而化甲基不同.
- 金属离子协调 (NO vs. OO) 和由此产生的zwitterionic结构受到金属离子大小和水分的影响.
结论:
- 通过单个水分子的水化足以稳定化氨酸的zwitterionic形式.
- 金属离子的大小 (Li+与Na+) 决定了水合 arginine 集群中不同的协调偏好和zwitterionic 结构.
- 化减弱金属离子-氨基酸相互作用,但通过强键增强zwitterionic结构的稳定性.
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