HIGH EXPRESSION OF SYNTHETIC HUMAN INTERFERON-GAMMA CDNA IN ESCHERICHIA-COLI

Human interferon-gamma (IFN-gamma) cDNA was synthesized, and it makes the usage of favorable codons in E. coli. The authors got 9 different expression plasmids which contain the synthetic IFN-gamma-cDNA and hav e different spaces between SD sequence and ATG. The free energies G(f2 98)(0) in the formation of stable secondary structure in the translati on initiation region (TIR) are different in various expression plasmid s. One of them, pLY(4)-gamma(5), can highly yield INF-gamma which will be about 60%-80% of the total bacterial proteins, such a high express ion was hardly noted in literature. The reasons of high expression in this work are optimal spaces between SD and ATC, favorable Delta G(f29 8)(0), favourable codons usage for E, coli. A simple and rapid method of purification of IFN-gamma was developed. The purity of IFN-gamma wi ll be over 95%, and the specific activity will be 2.0x10(7)IU/mg after islotation of inclusion body and one step chromatography.