ISOLATION AND IDENTIFICATION OF A NOVEL ALA-PRO-GLY-TRP-AMIDE-RELATEDPEPTIDE INHIBITING THE MOTILITY OF THE MATURE OVIDUCT IN THE CUTTLEFISH, SEPIA-OFFICINALIS

A novel myotropic neuropeptide was isolated from 110 optic lobes (OL) of mature females of the cuttlefish Sepia officinalis L. by mean of hi gh performance liquid chromatography (HPLC). The peptide inhibits the motility of the oviduct by decreasing the tonus, the frequency and the amplitude of the contractions. The primary structure of the peptide w as determined as Gly-Trp-NH2. This new dipeptide is closely related to the Ala-Pro-Gly-Trp-NH2 family first identified in gastropod molluscs . On the perfused oviduct, GWa appeared to be 3000 times more potent t han APGW-amide. The processing of synthetic APGWa into GWa by diaminop eptidyl activity has been clearly observed in OL extract. Nevertheless , the analysis in MALDI-MS of HPLC OL fractions did not reveal any APG Wa related peptides of the known : APGWa, KPGWa, RPGWa and TPGWa. GWa could be processed from a not yet identified APGWa related peptide. (C ) 1997 Elsevier Science Inc.