Purification and sequence determination of bovine atrial natriuretic factor

We report the purification and the sequence determination of bovine atrial natriuretic factor (ANF) in acid extracts of bovine atrial appendages. The monitoring of the activity along the purification steps was performed with a radio-receptor assay using bovine adrenal cortex membranes sites and 125I ANF. Bovine ANF was separated by carboxymethyl agarose gel chromatography from catecholamines and major protein contaminants. It behaved as a 3 K dalton peptide on Sephadex G-50. The active fractions were then subjected to high performance liquid chromatography (HPLC) using a sulfopropyl cation exchange column. Subsequent purification steps by reverse phase mode on Ultrapore RPSC, Vydac TP 218 and uBondapak using acetonitrile gradients led to the obtention of a pure fraction which amino acid sequence was identical to that for human ANF. This confirms the high degree of homology of ANF structure among mammalian species and advocates the use of the radio-receptor assay based on bovine adrenal receptor for measuring human ANF.