HEPARIN-RELEASABLE PROATRIAL NATRIURETIC PEPTIDE PROCESSING ENZYME FROM BOVINE ATRIA

Abstract

The proatrial natriuretic peptide (pro-ANP) processing enzyme, which catalyzes the conversion of pro-ANP to atrial natriuretic peptide (ANP), the active circulating form, was partially purified from bovine atria and characterized. The enzyme, which selectively cleaves the Arg(98)-Ser(99) peptide bond of pro-ANP, was released from the membrane fraction of atrial cells by heparin, suggesting that the enzyme is located at the outer surface of plasma membrane. The enzyme showed optimal pH of 8.0 and was strongly inhibited by serine protease inhibitors. The molecular weight was 560 kDa on gel filtration.