水溶液中氨基酸与二甲脲的混合焓及焓对相互作用  

The mixing enthalpies and enthalpic interactions of some amino acids with 1,3-dimethylurea in aqueous solutions at 298.15K.

作　　者：邵爽[1] 林瑞森[2] 

机构地区：[1]浙江教育学院化学系,浙江杭州310012 [2]浙江大学化学系,浙江杭州310027

出　　处：《浙江大学学报（理学版）》2001年第3期269-275,共7页Journal of Zhejiang University（Science Edition）

基　　金：国家自然科学基金资助项目!(2 0 0 730 39)

摘　　要：用 L KB- 2 2 77精密微热量计测定了 2 98.15K时甘氨酸、L-丙氨酸、L -丝氨酸、L -缬氨酸、L -苏氨酸和 L-脯氨酸 6种α-氨基酸分别与二甲脲分子在水溶液中混合过程焓变及这些溶质分子在水溶液中的稀释焓 ,根据 Mc Millan- Mayer理论关联得到各级交叉焓相互作用系数 .重点讨论了不同氨基酸与二甲脲分子的相互作用机制 .结果表明 ,氨基酸的两性离子部分、α-碳上的非极性脂肪侧基、极性的羟基侧基和五元吡咯环结构对交叉焓对作用系数 hxy具有不同贡献 .与尿素相比 ,二甲脲分子中 -The mixing enthalpies of 1,3 dimethylurea(DMU)and six kinds of amino acids (glycine, L alanine, L serine, L proline, L threonine, L valine) in aqueous solutions were determined at 298.15K by the LKB 2277 flow microcalorimetric system. These results along with enthalpies of dilution of these solutes for the initial solutions were used to determine the enthalpic interaction coefficients ( h xy , h xxy , etc.) in terms of the McMillan Mayer theory. The cross pairwise interaction coefficients ( h xy ) of amino acids and DMU were discussed. The results show that the different side groups of amino acids make their different contributions to h xy . The hydrophobic hydrophobic interactions of glycine, L alanine and L valine with DMU increase with the number of CH 2 groups on α carbon. The five membered pyrolidine ring in proline exhibits some hydrophobicity. The introduction of CH 3 groups makes the hydrophobicity of DMU stronger than that of urea.

关 键 词：Α-氨基酸 二甲脲 交叉焓相互作用 热力学 混合焓 相互作用机制 水溶液 

分 类 号：O642.1[理学—物理化学]