ISOLATION AND STRUCTURAL ELUCIDATION OF 8 KININS FROM THE RETROCEREBRAL COMPLEX OF THE AMERICAN COCKROACH, PERIPLANETA-AMERICANA

By monitoring the contractile activity of the hindgut of the American cockroach in vitro eight myotropic neuropeptides were isolated from th e retrocerebral complex of the American cockroach. Peptide sequence an alysis and mass spectrometry yielded the following structures: Arg-Pro -Ser-Phe-Asn-Ser-Trp-Gly-NH2 (Pea-K-1), Asp-Ala-Ser-Phe-Ser-Ser-Trp-Gl y-NH2 (Pea-K-2), Asp-Pro-Ser-Phe-Asn-Ser-Trp-Gly-NH2 (Pea-K-3), Gly-Al a-Gln-Phe-Ser-Ser-Trp-Gly-NH2 (Pea-K-4), Ser-Pro-Ala-Phe-Asn-Ser-Trp-G ly-NH2 (Pea-K-5), Asp-Pro-Ala-Phe-Ser-Ser-Trp-Gly-NH2 (Lem-K-7), Gly-A la-Asp-Phe-Tyr-Ser-Trp-Gly-NH2 (Lem-K-8) and Ala-Phe-Ser-Ser-Trp-Gly-N H2 (Lom-K). The C-terminal sequence Phe-X-Ser-Trp-Gly-NH2 characterize d the peptides as members of the insect kinin family. All structures w ere confirmed by comparison of retention times between synthetic and n atural peptides. The threshold concentration for stimulatory effects o f the synthetic peptides on the isolated hindgut was about 10(-9) M an d there was no significant difference measured between the different k inin forms. These neuropeptides are the first members of the insect ki nin-family isolated from the American cockroach. Their occurrence in t he retrocerebral complex suggests a physiological role as neurohormone . (C) 1997 Elsevier Science B.V