三种氨基酸在尿素-水混合溶剂中的体积性质  

Volumetric Property of Three Amino Acids in Urea-Water Mixtures

作　　者：马林[1] 许莉[2] 林瑞森[2] 魏志强[1] 刘东群[1] 

机构地区：[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

出　　处：《化学学报》2008年第1期129-137,共9页Acta Chimica Sinica

摘　　要：用精密密度法详细测定甘氨酸、L-丙氨酸、L-丝氨酸在尿素-水混合溶剂中的表观摩尔体积.计算了三种氨基酸从水到尿素-水混合溶剂的迁移偏摩尔体积,结合前期的氨基酸从水到尿素-水混合溶剂的迁移焓,探讨尿素-水混合溶剂的结构特点及其对氨基酸与尿素相互作用的影响.结果表明,尿素分子在水中自缔合,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-水混合溶剂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.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 inves- tigate the structural characteristics of the urea-water mixtures and their influence on the interaction between amino acids and urea on the basis of a 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 the self-association of urea molecules in the aqueous solution and its influence on the structure interaction with amino acids. The results also indicated that more hydrophobic amino acids had stronger dehydration effect due to the structure interaction with urea.

关 键 词：氨基酸 尿素 偏摩尔体积 相互作用 

分 类 号：O621[理学—有机化学]