α-氨基酸-丁醇-水三元体系中分子间的异系焓相互作用

利用2277热活性检测仪的流动测量系统获得了298.15K时甘氨酸、L-丙氨酸、L-缬氨酸和L-脯氨酸分别与n-丁醇在水溶液中混合过程的焓变以及各自的稀释焓,依据McMillan-Mayer理论关联得到异系焓相互作用系数,讨论了不同氨基酸与n-丁醇分子的作用机理.对hxy值分析结果表明,不同氨基酸与n-丁醇分子间的异系焓作用系数的大小主要取决于氨基酸分子结构的差异,氨基酸的不同侧基(非极性或极性)对焓作用系数有着不同的贡献,焓作用系数值的相对大小最终取决于各基团之间竞争平衡的结果.脯氨酸特殊的五元吡咯环结构对hxy值有较大的正贡献;n-丁醇的疏水性比尿素或甲脲大得多.

Heterotactic Enthalpic Interaction of Intramolecules in α-Amino Acids-n-Butanol-Water Ternery Systems at 298.15 K

Mixing and dilution heterotactic enthalpies of aqueous n-butanol solutions and aqueous amino acids(glycine, L-alanine, L-proline, L-valine) solutions were determined at 298.15 K by flow microcalorimetric system of 2277 Thermal Activity Monitor. The data were analyzed by using the McMillan-Mayer theory to obtain the enthalpic interaction coefficients. The interaction between different amino acids and n-butanol molecules has been discussed. It is demonstrated that h xy values between amino acids and the n-butanol depend on the structure of amino acids. The contributions of different side-groups of amino acids to h xy are different.The five-membered pyrrole ring of proline have a larger effect on h xy. The hydrophobicity of n-butanol is much greater than that of urea or monomethylurea.