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化学学报
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化学学报 ›› 2008, Vol. 66 ›› Issue (1): 129-137. 上一篇    下一篇

研究简报

三种氨基酸在尿素水溶液中的体积性质

马林*,1，许莉2，林瑞森2，魏志强1，刘东群1   

  1. (1广西大学化学化工学院 南宁 530004)
    (2浙江大学化学系 杭州 310027)
  • 投稿日期:2007-05-04 修回日期:2007-08-22 发布日期:2008-01-14
  • 通讯作者: 马林

Volumetric Property of Amino Acids in Aqueous Urea

MA Lin*,1 XU Li2 LIN Rui-Sen2 WEI Zhi-Qiang1 LIU Dong-Qun1   

  1. (1 College of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004)
    (2 Department of Chemistry, Zhejiang University, Hangzhou 310027)
  • Received:2007-05-04 Revised:2007-08-22 Published:2008-01-14
  • Contact: MA Lin

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精密密度法详细测定甘氨酸、L-丙氨酸、L-丝氨酸在尿素水溶液中的表观摩尔体积，计算了三种氨基酸从水到尿素水溶液的迁移偏摩尔体积，结合前期的氨基酸从水到尿素水溶液的迁移焓，探讨尿素水溶液的结构特点及其对氨基酸与尿素在水溶液中相互作用的影响。结果表明，尿素分子在水溶液中自缔合，引起溶剂结构的变化并削弱其与氨基酸分子的结构相互作用，造成氨基酸从水到尿素水溶液的迁移偏摩尔体积和迁移焓随尿素浓度的增加而出现多个变化点，这一效应随着氨基酸疏水性的增强而增大，表明氨基酸的疏水性越强，其与尿素相互作用引起的去水化作用越明显。

关键词: 氨基酸, 尿素, 偏摩尔体积, 相互作用

Apparent molar volumes of glycine, L-alanine and L-serine in aqueous urea at 298.15 K were determined and transfer partial molar volumes from water to aqueous urea were derived. The results, along with transfer enthalpies of amino acids from water to aqueous urea in our previous work, were used to investigate the characteristic of structure of urea-water mixtures and its influence on the interaction between amino acids and urea on the basis of hydration cosephere overlapping model. Regular breaks were found on the urea concentration dependence of transfer partial molar volumes and transfer enthalpies of amino acids, which was attributed to the change of solvent structure due to self-association of urea molecules in aqueous solution and its influence on the structure interaction with amino acids. The results also indicated that more hydrophobic amino acids undergo more dehydration effect due to the structure interaction with urea.

Key words: amino acid, urea, limiting partial molar volume, interaction