Chitosan/cellulose-based beads (CCBs) for the affinity purification of histidine-tagged proteins were prepared from chitosan/cellulose dissolved in ionic liquid as a solvent, and their structures were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. The affinity purification was used to separate hexahistidine-tagged (his-tagged) enhanced green fluorescent protein (EGFP) from Escherichia coli. The results showed that Zn2+-CCB exhibited more specific adsorption capacity toward the target protein compared with Ni2+-CCB and Cu2+-CCB. The maximum adsorption of EGFP was 1.84 mg/g of Zn2+-CCB, with 90% purity under the optimized conditions (ionic strength (1.0 M NaCl), pH (7.2) and imidazole concentration (500 mM)). In addition, a regeneration method for the sorbent was further developed by washing with ethylenediaminetetraacetic acid disodium and then reimmobilizing with metal ions. This technique is an alternative method for the purification of his-tagged proteins, making the process more economical, fast, stable, and large batch.
Keywords: Affinity purification; chitosan; his-tagged protein; ionic liquid; reuse.