金属离子种类对配体交换毛细管区带电泳法手性拆分5种氨基酸效果的影响

Effect of metal ions on enantioseparation of five amino acids by ligand exchange capillary zone electrophoresis

通过配体交换毛细管区带电泳法对5种氨基酸进行手性分离。采用不同金属离子和L-组氨酸按照一定比例形成具有手性识别作用的络合物,待分离对映体与络合物结构中的L-组氨酸配体进行交换。根据配体交换的难易程度实现手性对映体的分离。考察分离效果与金属离子的化合价或电子层数的关系。以4 mmol/L Co(Ⅱ)和8 mmol/L L-组氨酸作为缓冲体系(20 mmol/L的磷酸盐缓冲溶液,pH 8.0), 20 kV分离电压下,12 min内实现D,L-苯丙氨酸,D,L-酪氨酸,D,L-色氨酸的基线分离,分离度最大为1.53,2.04和1.58。丝氨酸和缬氨酸对映体可部分分离。以同电子层数和化合价的Cu(Ⅱ)和Zn(Ⅱ)为中心离子时,分离效果不及Co(Ⅱ)。而以1价Ag(Ⅰ)为中心离子时对氨基酸对映体分离效果不及2价金属离子,核外4层电子时分离能力不及3层电子。

Enantioseparation of five amino acids was conducted by chiral ligand exchange capillary zone electrophoresis(CLE-CZE).L-His and different metal ions in a certain proportion were used to form chiral recognition complexes.The enantiomers were exchanged with L-His ligands in the complex.Then,the separation of enantiomers was obtained according to the different ligand exchange ability.Effects of the valence and the electron layers of metal ions on the resolution were investigated systemically.Baseline separation of D,L-Phe,D,L-Tyr and D,L-Trp was obtained within 12 min when 4 mmol/L Co(Ⅱ)and 8 mmol/L L-His were added to the phosphate buffer solution(20 mmol/L,pH 8.0).The resolutions of D,L-Phe,D,L-Tyr and D,L-Trp were 1.53,2.04,and 1.58,respectively.Partial chiral separation of D,L-Ser and D,L-Val was achieved under the same conditions.When Co(Ⅱ)was used as the central ion,the resolution was better than that of Cu(Ⅱ)and Zn(Ⅱ),although they had the same number of electron layers and valence.The resolution of amino acids with Ag(Ⅰ)as the central ion was not as good as that of divalent metal ions.Metal ions with three electron layers had better separation results than that with four electron layers.