关键词: 甘氨酸, 丝氨酸, 天冬氨酸, α-氨基酸, 稀土络合物, NMR

Abstract: ¹³C shifts of amino acids, Gly、Ser and Asp,induced by lanthanide ions,La³⁺、Pr³⁺、Nd³⁺、Eu³⁺、Tb³⁺、Dy³⁺、Ho³⁺、Er³⁺、Tm³⁺ and Yb³⁺, were measured in acidicaqueous solution. An analysis of ¹³C lanthanide-induced shifts (LISs) indicates that these three amino acids are bidentately coordinated to Ln through their α-carboxyl groups with Ln-0 bond length of 0.23nm~0.25nm. γ-carboxyl group is also involved in coordination for aspartic acid. By systematically analyzing ¹³C LISs in this paper and previously reported for various α-amino acid-Ln complexes, the following general conclusions are drawn about hyperfine coupling constant A and geometric factor G for ligand carbon nuclei:
(l)|A(C₀)|<|A(C_α)|with a positive sign for A(C₀) and a negative one for A(C_α); (2) G values are negative for all ligand carbon nuclei with|G(C₀)|>|G(C_α)|.

Key words: Glysine, Serine, Aspartic acid, α-amino acid, Lanthanide complex, NMR