Selection conditions of the recombinant bovine α-interferon from E. coli inclusion bodies

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Like other proteins of the cytokine family, bovine α-interferon activates and modulates antiviral state of the target cells and inhibits division and growth of the infected cells which makes it an excellent candidate as a new antiviral therapeutic agent.This study is concerned with the determination of the optimal isolation, purification and refolding conditions of the recombinant bovine interferon-α (rbIFN-α) from inclusion bodies (IBs). Main methods used were UV/Visible spectroscopy, electrophoresis, liquid chromatography and refolding by dilution.It was found that two step IBs washing with solutions containing 50 mmol/l Tris, 50 mmol/l NaCl and 3.5 mol/l urea and their subsequent solubilization in 50 mmol/l Tris-HCl, pH 9.8 mol/l Urea and 20 mmol/l β-mercaptoethanol allow us to receive the target protein in monomeric form and 53.18 ± 9.3 % purity. Further application of the anion-exchange tandem chromatography on DE 52 cellulose and toyopearl DEAE-650 M gives a possibility to remove the major impurities and obtain rbIFN-α with 80.7 ± 8.6 % purity. Refolding by dilution in the buffer containing 20 mmol/l NaPB, рН 7.4, 0.4 mol/l sucrose, 1 mmol/l L-Cys, 0.1 mmol/l L-Cystine, 1 mmol/l EDTA, 0.05 % Kolliphor EL at 10 °C followed by the protein collection allows to get the recombinant rbIFN-α in homogeneous state, with 98.43 % purity and antiviral activity about (5 ± 3.6)•106 U/mg.