Evaluation of immobilized metal affinity chromatography kits for the purification of histidine-tagged recombinant CagA protein

• IMAC is used for the purification of 6xHis-tagged recombinant proteins.
• Commercially available three IMAC kits were evaluated.
• SDS was used to dissolve recombinant proteins forming insoluble inclusion bodies.
• Recombinant protein was equally purified by all kits under denaturing conditions.

Immobilized metal affinity chromatography (IMAC) technique is used for fast and reliable purification of histidine(His)-tagged recombinant proteins. The technique provides purification under native and denaturing conditions. The aim of this study is to evaluate three commercially available IMAC kits (Thermo Scientific, GE Healthcare and Qiagen) for the purification of a 6xHis-tagged recombinant CagA (cytotoxin-associated gene A) protein from IPTG-induced Escherichia coli BL21(DE3) culture. The kits were tested according to the manufacturer instructions and the protein was purified with only GE Healthcare and Qiagen kits under denaturing conditions. 1% (w/v) SDS was used as denaturing agent in PBS instead of extraction reagent of Thermo Scientific kit to lyse bacterial cells from 100 ml culture. The 6xHis-tagged recombinant protein was purified by the three kits equally.