Development of the method of isolation and purification of the recombinant human interleukin-7

Abstract

To develop a method for isolation and purification of recombinant human interleukin-7 from bacterial inclusion bodies. Methods. Protein synthesis via fermentation, densitometry, refolding method of gel filtration, two-stage chromatographic purification of the protein.Results. The inclusion bodies obtained via fermentation in E.coli cells contained recombinant human interleukin-7, which was solubilized at 22ºС for 1 hour in the following buffer solution: 7M of guanidine hydrochloride, 100mM of Tris-НСl, 0.1 % Tween-20 and 50mM of dithiothreitol. Renaturation was conducted by replacing the buffer on column XK26 / 40 (GE Healthcare) with Sephadex G-25 fine equilibrated Clark-Labs solution containing L-arginine hydrochloride and tween-20. Subsequent purification of rIL-7 on the gel filtration column was performed in two stages: at the first stage, purification of rIL-7 was performed on a column packed with 20 ml of Q sepharose, at the second stage, the rIL-7 fraction purified on Q sepharose was purified on SP sepharose. Elution of rIL-7 was performed using double-stage gradient NaCL (0.2 and 0.7M) in a buffer 0.05 M of KH 2 PO 4 /NaOH with pH 6.0; 0.1 М of L-arginine; 0.1 % Tween-80. Conclusions. The amount of the target protein after all the proposed stages of purification was 10 % with the purity ratio about 95 %, which is sufficient for further development of the various pharmaceutical forms.