金属离子与氨羧类螯合配体的键合特性研究

利用前沿色谱法,通过Cu2+、Ni2+和Co2+与螯合配体IDA 键合的准确度(R2>0.98)与精密度(RSD <5%)实验,研究了前沿色谱法同时测定络合稳定常数KML与总键合位点数Λ0值的可行性.为了进一步证明前沿色谱法的普适性,以Cu2+、Ni2+和Co2+为代表,在3种键合缓冲体系(NaAc-HAc、Na-PB、Tris-HCl)中,考察了金属离子在3种氨羧类螯合配体(IDA、Asp、Glu)上络合稳定常数KML的变化规律.结果表明,螯合配体对金属离子键合强度遵循IDA>Asp>Glu;金属离子对螯合配体键合强度遵循Cu2+>Ni2+>Co2+;3种键合缓冲体系中,NaAc-HAc键合效果最好.按照M06/6-311++G (d, p) 方法对螯合配体与金属离子的结合能(ΔE)与吉布斯自由能(ΔG)进行相关的量子计算.根据ΔE 与ΔG 的大小,从理论上推测出螯合配体与金属离子的键合规律,此规律与上述实验结果基本相符.本研究为金属离子与螯合配体间键合参数的求取提供了有效的方法和手段,从而为今后提高IMAC柱的稳定性,解决固定金属亲和柱在应用过程中尤其是竞争洗脱过程中金属离子的流失问题奠定了良好的基础.

Study on Binding Characteristics of Aminocarboxyl Chelating Ligands for Metal Ions

The feasibility of frontal chromatography for determining the complexation stability constant KML and total mole of binding site Λo was demonstrated by the accuracy and precision binding experiments between metal ions (Cu2+, Ni2+ and Co2+) and chelating ligand (IDA), in which R2>0.98 and RSD <5%.To further prove the universality of the frontal chromatography, the changing rules of KML values between Cu2+, Ni2+, Co2+ and IDA, Asp, L-Glu were examined under NaAc-HAc, Na-PB and Tris-HCl buffer systems.The results showed that the binding strength of chelating ligands for metal ions followed IDA>Asp>Glu;binding strength of metal ions for chelate ligands followed Cu2+>Ni2+>Co2+;and the binding effect with NaAc-HAc buffer was the best.In aqueous solution, quantum computing of binding energy (ΔE) and gibbs free energy (ΔG) between chelating ligand and metal ion was performed at the M06/6-311++G (d, p) level.According to ΔE and ΔG, the binding rules between chelating ligand and metal ion were predicted theoretically.These rules were basically in agreement with above experimental results.The present work provided effective method for studying on binding characteristics of metal ions for aminocarboxyl chelating ligands, thus exhibited a good foundation for improving the stability of immobilized metal affinity chromatographic column and solving the leakage of metal ions from the column in the process of competitive elution.