...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The Proton Affinity and Entropy of Protonation of Lysinamide. The Effects of Intramolecular Proton Solvation
【24h】

The Proton Affinity and Entropy of Protonation of Lysinamide. The Effects of Intramolecular Proton Solvation

机译：赖氨酰胺的质子亲和力和质子化熵。分子内质子溶剂化的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The equilibrium constants for the gas-phase proton transfer from protonated tri-n-propylamine to lysinamide at several temperatures have been measured using Fourier transform ion cyclotron resonance mass spectrometric techniques. The thermodynamic values obtained from a van't Hoff plot are ΔH = -4.36 ± 0.85 kcal mol~(-1), and ΔS = -12.25 ±2.34 cal mol~(-1) K~(-1). These values lead to derived values of the proton affinity (PA) and entropy of protonation (ΔS_p) of lysinamide of 241.4 ± 0.9 kcal mol~(-1) and 10.9 ± 2.2 cal mol~(-1) K~(-1), respectively. A sophisticated calculation in the literature suggests that the former is identical with the PA of lysine as would be expected. The PA of lysinamide exceeds that of 1,5-diaminopentane by 2.5 kcal mol~(-1), which is consistent with an expected favorable interaction between the carbonyl oxygen of the CONH_2 group and the strong hydrogen bond in protonated lysinamide. The ΔS_p values is in good agreement with a kinetic-method determination of the entropy of protonation of lysine. It is suggested that the currently accepted PA of lysine, which was determined by the kinetic method, is 3-4 kcal mol~(-1) too low. This discrepancy is suggested to be the result of the fact that the kinetic method measures activation entropies and enthalpies, rather than overall entropies and enthalpies, and thereby fails to measure the intramolecular proton-solvating interaction of the carbonyl group in lysine.
机译：使用傅里叶变换离子回旋共振质谱技术已经测量了在几个温度下气相质子从质子化的三正丙胺转移到赖氨酰胺的平衡常数。从范霍夫图获得的热力学值为ΔH= -4.36±0.85 kcal mol〜（-1），ΔS= -12.25±2.34 cal mol〜（-1）K〜（-1）。这些值导致派生的赖氨酰胺的质子亲和力（PA）和质子化熵（ΔS_p）分别为241.4±0.9 kcal mol〜（-1）和10.9±2.2 cal mol〜（-1）K〜（-1） ， 分别。文献中的复杂计算表明，正如预期的那样，前者与赖氨酸的PA相同。赖氨酰胺的PA比1，5-二氨基戊烷高2.5 kcal mol-（-1），这与CONH_2基团的羰基氧与质子化赖氨酰胺中强氢键之间预期的有利相互作用相一致。 ΔS_p值与赖氨酸质子化熵的动力学方法测定非常吻合。建议通过动力学方法测定的目前赖氨酸的PA太低了3-4 kcal mol〜（-1）。该差异被认为是以下事实的结果：动力学方法测量活化熵和焓，而不是总熵和焓，从而不能测量赖氨酸中羰基的分子内质子-溶剂化相互作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号