Isolation, identification and synthesis of locustamyotropin (Lom-MT), a novel biologically active insect peptide.

A peptide that stimulates the spontaneous contractions of the hindgut of Leucophaea maderae has been purified from extracts of brain-corpora cardiaca/corpora allata-subesophageal ganglion complexes of 9000 adult Locusta migratoria and was designated locustamyotropin or Lom-MT. The primary structure of this 12 residue peptide has been determined Gly-Ala-Val-Pro-Ala-Ala-Gln-Phe-Ser-Pro-Arg-Leu-NH2. The C-terminal sequence (Phe-Ser-Pro-Arg-Leu-NH2) is identical to the C-terminal pentapeptide of the pheromone biosynthesis activating neuropeptide, recently isolated from Heliothis zea, and is also similar to the C-terminal of leucopyrokinin of Leucophaea. Synthetic Lom-MT showed biological as well as chemical characteristics, indistinguishable from those of native Lom-MT. In locust preparations, Lom-MT provoked an increase in frequency, amplitude and tonus of contractions of the oviduct, but was inactive in the same conditions on the locust hindgut preparation.