Peptides having atrial natriuretic factor activity

A peptide having the amino acid sequence:

• ##STR13## wherein R is H, Ac, Ser, Ser-Ser, Arg-Ser-Ser, Arg-Arg-Ser-Ser, or Ser-Leu-Arg-Arg-Ser-Ser;
• A is Phe or N-MePhe;
• B is Gly, D/L-Ala or D/L-Pro;
• C is Gly, L-Ala or D/L-Pro;
• or
• B-C is ##STR14## where n=1 or 2, and
• R.sup.1 is H or methyl;
• D is Arg, N-MeArg or D/L-Pro;
• E is Arg, N-MeArg or Pro;
• F is Gly, D/L-Ala or D/L-Pro;
• G is Ala, N-MeAla or D/L-Pro, or
• F-G is ##STR15## wherein n=1 or 2, and
• R.sup.1 is H or methyl;
• H is Gln or D/L-Pro;
• I is Gly, D/L-Ala or D/L-Pro;
• J is Gly, D/L-Ala or D/L-Pro;
• K is D/L-Asn, D/L-Pro or D/L-N-MeAla;
• L is D/L-Ser, D/L-Pro or D/L-N-MeAla;
• M is D/L-Phe, D/L-N-MePhe or D/L-Pro;
• N is Met, Ile, Leu or Nle
• O is Asp or Glu;
• P is D/L-Arg, NH.sub.2 or is absent;
• Q is D/L-Tyr, NH.sub.2 or is absent;
• with the proviso that one residue of said peptide shall be N-methylated, said N-methylated residue taken from the group consisting of N-MePhe at position A, N-MeArg at position D, N-MeArg at position E, N-MeAla at position G, D/L-N-MeAla at position K, D/L-N-MeAla at position L and D/L-N-MePhe at position M;
• with the additional proviso that, when all other residue positions are identical to native ANP, M is not N-MePhe, K is not Pro or C is not Pro.