[Over expression of alpha-hANP in two kinds of expression systems of Escherichia coli].

Two kinds of expression plasmids carried Ref-Adaptor-(alpha-hANP) hybrid gene have been constructed. The adaptor GAA is the codon of glutamic acid which is a recognition site of the endoproteinase Glu-C. The expression of the heterologous fusion gene was controlled by the bacteriophage lambda PL promoter in the Escherichia coli expression system which is affected by the cIts857 repressor. These overproduced proteins were found in the form of inclusion bodies and constituted 35% and 48% of the total cellular protein respectively. The fusion protein was isolated and cleaved with Glu-C to liberate mature alpha-hANP, which demonstrated significant activities for reduction of blood pressure and vasorelaxation comparable to that of the chemically synthesized hormone. In this paper, the comparison between the two kinds of expression systems is also discussed.