甘氨酸主要存在于超和水溶液中的单体,而不是二体:对于理解其结晶和多形态的含义
Jun Huang1, Thomas C Stringfellow, Lian Yu
1School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705-2222, USA.
Journal of the American Chemical Society
|September 26, 2008
概括
甘氨酸存在于超和溶液中的单体,而不是二聚体,挑战了关于其结晶行为的先前假设. 这一发现影响了我们对氨基酸自我关联和多态性的理解.
科学领域:
- 物理化学 物理化学
- 晶体学 晶体学是指结晶学.
- 生物物理学的生物物理.
背景情况:
- 甘氨酸,最简单的氨基酸,以前被认为在超和溶液中形成二元体,影响其结晶成为特定的多态 (α).
- 这种自我关联被认为是将解决方案行为与多态选择性联系在一起的一般原则.
研究的目的:
- 为了研究糖氨酸在超和水溶液中的溶液状态.
- 为了确定甘氨酸是否存在于单体或二元体,并评估潜在二元体的稳定性.
- 重新评估老化对甘氨酸扩散的影响,此前作为二分化证据.
主要方法:
- 结点低压测量高达30%的超和.
- 脉冲梯度旋回回声核磁共振 (NMR) 光谱测量扩散.
- 斯托克斯-爱因斯坦关系应用于扩散性和粘度数据.
主要成果:
- 甘氨酸主要以单体的形式存在于超和溶液中,其二元稳定常数 (K D) 低于0.1 kg H2O/mol.
- 没有观察到对甘氨酸扩散的老化影响,在五天内高达24%的超和.
- 计算的溶解物大小没有随着度或溶液年龄的增加而增加,这表明单质的行为.
结论:
- 甘氨酸主要以单体形式存在于超和水溶液中,并且不表现出与二分化相关的衰老效应.
- 这一发现需要重新评估在正常情况下α-甘氨酸是首选的多态体的假设.
- 这项研究挑战了自我关联的建议一般原则,决定了甘氨酸的多态选择性.
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