Grafting glycidyl methacrylate-iminodiacetic acid conjugate to Sepharose FF for fabrication of high-capacity protein cation exchangers

Abstract This work was designed to acquire novel high-capacity cation exchangers by grafting glycidyl methacrylate (GMA)-iminodiacetic acid (IDA) conjugate (GMA-IDA) to Sepharose FF. Six GMA-IDA-grafted resins of the same grafting density but different chain lengths (ionic capacities, ICs) were synthesized and denoted as FF-Br2-pG-I n ( n denotes for IC value). Lysozyme adsorption and chromatography were studied to evaluate the cation exchangers. It was found that resins of moderate IC values (FF-Br2-pG-I480 and FF-Br2-pG-I590) afforded lysozyme adsorption capacities higher than 300 mg/mL at 50 and 100 mmol/L NaCl, over three times higher than the commercial resin CM Sepharose FF. Beside, the uptake rate ( D e / D 0 ) of lysozyme decreased with increasing IC at 50 mmol/L NaCl because of the increased polymer chain length that limited surface diffusion of the bound protein. Protein adsorption capacities of FF-Br2-pG-I480 and FF-Br2-pG-I590 kept higher than that of CM Sepharose FF in the salt concentration range of 0–150 mmol/L, and the uptake rates on the two resins increased with increasing salt concentration. Therefore, the dynamic binding capacities of them were remarkably higher than that of CM Sepharose FF and kept over 70 mg/mL at the salt concentration up to 150 mmol/L. The results demonstrated that GMA-IDA-grafted resins are promising for use as high-capacity protein chromatography.