Human atrial natriuretic polypeptides (hANP): purification, structure synthesis and biological activity.

In the present survey for natriuretic factors in human atrial extract, conducted by using in vitro assay for the relaxant activity of chick rectum, three distinct human atrial natriuretic polypeptides (hANP) (alpha-, beta- and gamma-hANP), differing in molecular weight (alpha, 3000; beta, 6000, gamma, 13 000 daltons) have been purified and sequenced. gamma-hANP, of 13 000 daltons, has been identified as a 126-residue peptide which carries the whole sequence of alpha-hANP of 28-amino acids at the C-terminus, while beta-hANP has been proved to be an antiparallel dimeric form of alpha-hANP. Synthetic alpha-hANP at a dose of 0.2 nmol induces diuresis and natriuresis as well as hypotension, when injected into assay rats [1]. Natriuretic activity of beta- and gamma-hANP was estimated to be about one-fifth or less on molar base than that of alpha-hANP.