Alginate-grafted Sepharose FF: A novel polymeric ligand-based cation exchanger for high-capacity protein chromatography

Abstract

This work was designed to acquire a new high-capacity cation-exchange chromatography resin of protein by modification of Sepharose FF gel with sodium alginate. Three cation exchangers of different ionic capacities (ICs, 140–240mmol/L) were synthesized, and the alginate-based resins, denoted as Alg-FFs, were studied for lysozyme (Lys) adsorption and chromatography. It was found that the adsorption capacity and effective protein diffusivity of Lys increased with increasing alginate-grafting density or the IC value. The resin with the highest IC value (240mmol/L), Alg-FF-240, was compared with a commercial cation exchanger, CM Sepharose FF. It revealed that both protein adsorption capacity and uptake rate of Alg-FF-240 were remarkably higher than CM Sepharose FF at NaCl concentrations lower than 100mmol/L, so the dynamic binding capacity (DBC) of Alg-FF-240 was much higher than CM Sepharose FF at the salt concentration range. Moreover, the DBC of Alg-FF-240 maintained high level at the flow rate up to 1350cm/h, and at the highest flow rate studied, the DBC of Alg-FF-240 for Lys was about 1.7 times higher than that on CM Sepharose FF. Salt-gradient elution revealed similar protein elution behaviors on the Alg-FF-240 and CM Sepharose FF columns. Altogether, the findings in this research indicate that alginate-based cation exchangers deserve further development for high-performance protein chromatography.