The vasoactive intestinal peptide (VIP): VI. The 17-norleucine analog of the sequence 14–28

Abstract

A pentadecapeptide amide with the C-terminal sequence (14–28) of the vasoactive intestinal peptide (VIP), but with the methionine residue in position 17 replaced by l-norleucine, was synthesized. The synthesis was carried out through stepwise chain lengthening, by the in situ technique. The norleucine-containing pentadecapeptide, l-arginyl- l-lysyl- l-glutaminyl- l-norleucyl- l-alanyl- l-valyl- l-lysyl- l-lysyl- l-tyrosyl- l-leucyl- l-asparaginyl- l-seryl- l-isoleucyl- l-leucyl- l-asparaginamide, was as active in relaxing different smooth-muscle preparations as the methionine-containing parent sequence.