| Abstract: | With the objective of identifying specific peptidase responsible for the processing of atrial natriuretic factor precursor pro-ANF to the circulating active form ANF (99-126), a fluorometric assay method was devised using synthetic fluorogenic substrate Boc-Ala-Gly-Pro-Arg-MCA(methylcoumarinamide) which contains the amino acid sequence immediately adjacent to the arginyl peptide bond which is cleaved in the natural processing of pro-ANF. A protease which selectively cleaves this bond and produces the natural circulating peptide was identified in the particulate fraction of rat atrial homogenate and was solubilized by 1.6 M KCl. It was partially purified by affinity chromatography heparin-agarose column and was shown to be a serine protease. Its reaction product with natural pro-ANF was identified as ANF (99-126) containing 28 amino acid residues. |
