Proadrenomedullin N-terminal 20 peptide is rapidly cleaved by neutral endopeptidase

Proadrenomedullin N-terminal 20 peptide (PAMP) is a novel hypotensive peptide which is processed from an adrenomedullin precursor. PAMP is rapidly cleaved by human neutral endopeptidase (NEP), a protease which plays a key role in the degradation of human atrial natriuretic peptide (ANP). A double reciprocal plot indicated that Km of NEP as a substrate of PAMP was 6.1 microM and V(max) was 3.1 mmol/min/mg of NEP. EDTA, phosphoramidon and thiorphan inhibit the proteolysis of PAMP by NEP. NEP cleaves at least 6 peptide bonds in human PAMP; Arg2-Leu3, Glu8-Phe9, Lys12-Trp13, Lys15-Trp16, Trp16-Ala17 and Ala17-Leu18. The present data suggest that NEP may be involved in the circulation control by degrading PAMP as well as ANP.