水溶液中稀土离子与甘氨酰丙氨酸作用的NMR研究

NMR STUDY OF INTERACTION BETWEEN DIPEPTIDE GLY-ALA AND LANTHANIDE IONS IN AQUEOUS SOLUTION

利用~1H和^(13)C NMR技术研究了水溶液中稀土离子与二肽甘氨酰丙氨酸(以下简称甘-丙二肽,记为GA)的配位作用。由稀土诱导位移的浓度依赖关系计算了Yb与甘-丙二肽配合物的稳定常数。测定了重稀土离子Dy^(3+)、Ho^(3+)、Er^(3+)、Tr^(3+)和Yb^(3+)作用下GA的^(13)C诱导位移,并根据Reuben方法对稀土诱导位移进行了线性相关分析。对配合物中配体骨架构象的模拟分析指出,Cl-C_2-N-C_3为旁式,C_2-N-C_3-C_4和C_5-C_2-N-C_3为反交叉式。系统比较了4种含甘氨酰二肽的侧基大小对配合物稳定常数、配体构象和配合物溶液结构的影响。

~1H and ^(13)C NMR techniques were used to study complexation of lanthanide ions with Gly-Ala in aqueous solution. For Yb complex with Gly-Ala the stability constant was calculated from the concentration dependence of lanthanide-induced shifts. ^(13)C shifts induced by heavy lanthanide ions Dy^(3+), Ho^(3+), Er^(3+), Tm^(3+) and Yb^(3+) were analyzed by Reuben's method. The simulation for ligand conformation of lanthanide complex with Gly-Ala shows that the ligand segment C1-C2-N-C3 is in gauche form,while the segments C2-N-C3-C4 and C5-C2-N-C3 in trans form. The effects of side-group size of several glyeine-eontaining dipeptides on complex stability constants, ligand conformations and structure of complexes in solution were discussed.