物理化学学报2000，Vol.16Issue(2)：188-192,5.
α-氨基酸在水-乙醇中羧基质子化热力学
Thermodynamics of Carboxyl Group′s Protonation of α -amino Acids in Water-Ethanol Mixtures at 298.15K
摘要
Abstract
Enthalpy changes for the protonation of carboxyl group of four α-amino acids(glycine,L-α-alanine,L-valine and L-serine) were measured in water-ethanol mixtures (10－ 70wt％) at 298.15K using LKB-2277 Bioactivity Monitor.The corresponding entropy and Gibbs energy changes were also calculated.The results show that both enthalpy changes and entropy changes are favorable to the protonation of carboxyl groups of the investigated amino acids in water-ethanol mixtures.However,the influence of the composition of ethanol in the mixed solvents on the enthalpy change and entropy changes is complicated.Both sδ and sδ ,the differences of enthalpy changes and entropy changes in mixed solvents and in pure water respectively,show a minimum approximately at xEtOH=0.1.The effects of side chains on the enthalpy change and entropy changes were also investigated using the proton transfer process between glycine and the other three amino acids.The results demonstrate that the proton transfer processes for alanine and valine are spontaneous but not for serine,which could be interpreted in terms of the electrostatic interaction between amino group and carboxyl group within the molecule and the interaction between carboxyl group and the solvent.关键词
质子化焓/α-氨基酸/羧基/混合溶剂Key words
Enthalpy of protonation/Amino acids/Carboxyl groups/Mixed solvents分类
社会科学引用本文复制引用
厉刚,林瑞森,宗汉兴..α-氨基酸在水-乙醇中羧基质子化热力学[J].物理化学学报,2000,16(2):188-192,5.基金项目
国家自然科学基金资助项目(29773041) （29773041）
