ISOLATION, IDENTIFICATION AND SYNTHESIS OF LOCUSTAMYOTROPIN-II, AN ADDITIONAL NEUROPEPTIDE OF LOCUSTA-MIGRATORIA - MEMBER OF THE CEPHALOMYOTROPIC PEPTIDE FAMILY

An eight residue neuropeptide (Glu-Gly-Asp-Phe-Thr-Pro-Arg-Leu-NH2) has been isolated from an extract of 9000 brain corpora cardiaca-corpora allata-suboesophageal ganglion complexes of Locusta migratoria. Biological activity was monitored during HPLC purification by observing the myotropic effect of column fractions on the isolated hindgut of Leucophaea maderae. The peptide designated as locustamyotropin II, or Lom-MT II according to Raina and Gäde (Insect Biochem. 18, 785-787, 1988), has a Phe-X-Pro-Arg-Leu-NH2 carboxyl-terminal in common with the previously identified locustamyotropin I. Locustamyotropin II is also related to leucopyrokinin (Lem-PK), a blocked myotropic neuropeptide isolated from cockroach heads. Both peptides have identical carboxyterminal pentapeptide sequences. The constituent amino acids of this C-terminal are important for biological activity on the Leucophaea hindgut. Lom-MT II differs from Lem-PK in the first three aminoterminal residues. In contrast to Lem-PK and like Lom-MT I, the novel locust peptide is not N-terminally blocked. Lom-MT II has a stimulatory effect on the motility of the oviduct of Locusta but not on the hindgut. © 1990.