Abstract:

The partially neutralized poly(ethylenimine)-grafted Sepharose FF, FF-PEI-R440, exhibited higher protein capacity and faster uptake rate than its starting resin FF-PEI-L740. In this work, the influence of counterions on protein adsorption onto and elution from the FF-PEI-R440 resin was investigated with sodium salts of SCN^-, Cl^-, HPO₄^2- and SO₄^2- at ionic strengths of 0.03 mol·L^-1 and 0.06 mol·L^-1. It was found that the static adsorption equilibrium of FF-PEI-R440 was significantly influenced by the counterions, and the adsorption capacity increased in the order of SCN^- < SO₄^2- < HPO₄^2- < Cl^- at the two ionic strengths. At the low ionic strength, the counterions had no significant effect on the uptake rate and dynamic binding capacity except for SCN^-. At high ionic strength, the uptake rate increased in the order of SCN^- < SO₄^2-≈Cl^- < HPO₄^2-. Dynamic binding capacity increased in the order of SCN^- < SO₄^2- < HPO₄^2- < Cl^-, the same of the order of adsorption capacity. The dynamic binding capacity kept the highest values when Cl^- existed at the two ionic strengths. Protein elution was little affected by counterions. The results indicated that the adsorption performance of FF-PEI-R440 was affected by counterions and the Cl^- was the most favorable couterion for column operation.

Key words: ion exchange chromatography, polymer grafting, counterion, adsorption equilibrium, kinetics, dynamic binding capacity, linear gradient elution

摘要：

前期研究表明部分电荷中和的聚乙烯亚胺接枝琼脂糖介质FF-PEI-R440具有较高静态吸附容量和快速传质速率。本文选取硫氰酸根离子、氯离子、磷酸氢根离子以及硫酸根离子这4种反离子，在离子强度为0.03、0.06 mol·L^-1下，研究其对FF-PEI-R440吸附与洗脱行为的影响。结果表明：在两种离子强度下，饱和吸附容量的增加顺序均为SCN^- < SO₄^2- < HPO₄^2- < Cl^-；在低离子强度下，除SCN^-外，反离子种类对传质速率和动态结合容量没有显著影响；在高离子强度下，传质速率的增加顺序为SCN^- < SO₄^2- ≈ Cl^- < HPO₄^2-，而动态结合容量的增加顺序与饱和吸附容量序列一致；两种离子强度下Cl^-均保持最高的动态结合容量；反离子种类对蛋白质洗脱行为没有显著影响。上述结果说明反离子主要影响FF-PEI-R440的吸附性能，而不影响洗脱，且流动相中选择Cl^-为反离子最利于FF-PEI-R440的实际柱色谱操作。

关键词: 离子交换色谱, 聚合物接枝, 反离子, 吸附平衡, 动力学, 动态结合容量, 线性梯度洗脱