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本文用~(13)C NMR方法研究了水溶液中三价顺磁性稀土离子Ho~(3+)和Yb~(3+)与二肽甘氨酰替亮氨酸之间的相互作用。对稀土诱导位移中的接触位移和偶极位移进行了分离。实验表明,与羧基相连的碳核所受的接触作用很大,因此不能把镱诱导的位移直接用于肽的构象分析。在水溶液中,肽通过羧基与稀土离子配位,在弱酸性条件下肽键和氨基均不参与配位。根据结构因子确定了肽在溶液中的构象,结果表明,分子片段C1-C2-C5-C6,C2-N-C3-C4和C2-C5-C6-C8为反式,而C2-C5-C6-C7和C1-C2-N-C3成旁式。
In this paper, the interaction between the trivalent paramagnetic rare earth ions Ho 3+ and Yb 3+ and the dipeptide glycyl leucine in aqueous solution was studied by ~ (13) C NMR. The contact displacement and dipole displacement in the rare earth induced displacement were separated. Experiments show that the carbon-linked carbon nuclei are exposed to a large amount of contact and therefore, ytterbium-induced displacement can not be used directly for peptide conformational analysis. In aqueous solution, the peptide coordinates with the rare earth ion through the carboxyl group, and the peptide bond and the amino group are not involved in the coordination under weakly acidic conditions. The conformation of the peptide in solution was determined on the basis of the structural factors and the results showed that the molecular fragments C1-C2-C5-C6, C2-N-C3-C4 and C2-C5-C6-C8 are trans and C2-C5-C6 -C7 and C1-C2-N-C3 into the formula.