Non-amidated forms of VIP (glycine-extended VIP and VIP-free acid) have full bioactivity on smooth muscle.
The aim of the present study was to elucidate the importance of the C-terminal amide group for the biological activity of vasoactive intestinal peptide (VIP). Two synthetic peptides lacking the amide group: VIP having a carboxyl group at the C-terminus and the intermediate biosynthetic precursor, glycine-extended VIP were compared with VIP itself regarding the ability to inhibit spontaneous activity in smooth muscle strips from rat stomach and human Fallopian tube. Both the glycine-extended VIP and VIP having a carboxyl group at the C-terminus caused a significant and dose-dependent inhibition of smooth muscle activity and displayed dose-response curves similar to VIP. The potencies of the VIP variants did not differ significantly from that of VIP. Thus, alpha-carboxyamidation of VIP is not a prerequisite for biological activity.
Fahrenkrug
J
J
Department of Clinical Chemistry, Bispebjerg Hospital, University of Copenhagen, Denmark.
Ottesen
B
B
Palle
C
C
D000818:Animals; D005187:Fallopian Tubes / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005998:Glycine / Q000494:pharmacology*; D006801:Humans; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
D014660:Vasoactive Intestinal Peptide; D005998:Glycine