Development of an antagonist of molluscan neuropeptide APGWamide with a peptide library

Fifty-seven kinds of APGWamide-related peptides and a peptide library consi sting of 38 peptide mixtures, each of which contained 19 kinds of APGWamide -related peptides, were synthesized with a multipeptide synthesizer, and th eir APGWamide-agonistic or -antagonistic effects were examined on the anter ior byssus retractor muscle of the bivalve Mytilus edulis and the crop of t he land snail Euhadra congenita. The peptide mixtures having agonistic or a ntagonistic effects were subjected to HPLC purification to isolate the acti ve peptides using the muscles as bioassay systems. Many peptides having ago nistic or antagonistic effects were obtained. Of the antagonists, APGWGNami de, isolated from the peptide mixture of APGWGXamide, was the most potent. At 10(-4) M, APGWGNamide almost completely blocked the actions of 10-(6) M APGWamide on the anterior byssus retractor muscle of M. edulis and the crop of E. congenita. (C) 2000 Elsevier Science Inc. All rights reserved.