[Isolation of a group of hybrid proteins consisting of tumor necrosis factor alpha and thymosin alpha 1].

New plasmid DNA coding for the synthesis of three hybrid proteins differing by the position of alpha 1-thymosin at N- and C-terminals of tumor necrosis factor were optimized and constructed. The instability of plasmids at culturing of E. coli strains stored in solid nutrient media was demonstrated. Newly obtained transformants and preserved cells were cultured, this providing a high level of synthesis of hybrid proteins. The effects of culturing temperature and protein structure on protein solubility were shown. Hybrid proteins were purified by chromatography on hydrophobic anion-exchange carriers and blue agarose in the presence of 7 M urea. After dialysis the proteins displayed different cytotoxicity in L-929 cells and were fit for immunobiological studies.