Soluble Prokaryotic Expression and Purification of Human Interferon Alpha-2b Using a Maltose-Binding Protein Tag

Human interferon alpha-2b (IFN alpha-2b) has therapeutic applications as an antiviral and antiproliferative drug and has been used for a wide range of indications. Efficient production of IFN alpha-2b in Escherichia coli has been difficult because the protein tends to form inclusion bodies. This obstacle has garnered interest in efficiently expressing IFN alpha-2b and overcoming its poor solubility. In this study, seven N-terminal fusion partners-hexahistidine (His6), thioredoxin, glutathione S-transferase (GST), maltose-binding protein (MBP), N-utilization substance protein A, protein disulfide bond isomerase (PDI), and b'a' domain of PDI - were tested for soluble overexpression of codon-optimized IFN alpha-2b in E. coll. Low temperature increased the expression level of all of the tagged proteins except for the GST fusion. All the tags, except for His6 and GST, improved solubility. We purified IFN alpha-2b from the MBP-tagged fusion using immobilized metal affinity chromatography and anion exchange chromatography, and obtained a final yield of 7.2 mg from an initial 500-ml culture. The endotoxin level was 0.46 EU/mu g. Biological activity was demonstrated using a I uciferase assay, which showed a dose-dependent response with a calculated EC50 of 10.3 +/- 5.9 pm. Our results demonstrate that using an MBP-tagged fusion is an efficient way to produce pure IFN alpha-2b. (C) 2016 S. Karger AG, Basel.