Expression, purification, and in vivo activity of atrial natriuretic factor prohormone produced in Escherichia coli

Atrial muscles of the heart are known to produce polypeptide hormones called atrial natriuretic factors (ANF) which have potent diuretic and hypotensive action. These hormones are synthesized as a larger protein precursor called pro atrial natriuretic factor or proANF which contains the biologically active ANF sequences at its C-terminus. Rat proANF (representing amino acids -1 to 128 of the coding sequence) was expressed in a soluble form in Escherichia coli. A simple purification procedure was developed which consists of boiling E. coli cell extracts in 1 M acetic acid and subjecting the supernatant to reversed-phase HPLC. The effect of intravenous administration of the purified recombinant proANF on mean arterial blood pressure was examined. The displacement dose-response curves obtained demonstrated that proANF exhibits similar, albeit less potent, physiological activity than ANF.