THE SEQUENCES OF 5 NEUROPEPTIDES ISOLATED FROM LIMULUS USING ANTISERATO FMRFAMIDE

Five neuropeptides were isolated from CNS extracts of the horseshoe cr ab Limulus polyphemus by high pressure liquid chromatography (HPLC). T he peptides were identified by radioimmunoassays (RIAs) based on two a ntisera raised to FMRFamide-related peptides (FaRPs). The purified pep tides were analyzed by automated sequencing and mass spectrometry, and the following sequences were obtained: DEGHKMLYFamide, GHSLLHFamide, PDHHMMYFamide, DHGNMLYFamide, and GGRSPSLRLRFamide. The first four pep tides are members of a novel family with virtually no relationship to FMRFamide. GGRSPSLRLRFamide, on the basis of structural similarity, be comes the second member of a class of FaRPs known previously only from a peptide isolated from mosquito heads. At least one member of the no vel family (GHSLLHFamide) inhibits the isolated heart of Limulus.