The metabolic neuropeptides of the corpus cardiacum from the potato beetle and the American cockroach are identical.

Two neuropeptides with adipokinetic activity in Locusta migratoria and hypertrehalosaemic activity in Periplaneta americana were purified by high performance liquid chromatography from the corpus cardiacum of the Colorado potato beetle, Leptinotarsa decemlineata. The sequences of both peptides, designated Led-CC-I and Led-CC-II, were determined by pulsed-liquid phase sequencing employing Edman degradation after deblocking enzymatically the N-terminal pyroglutamate residue. The C-terminal of both peptides were blocked and neither molecule was cleaved by carboxypeptidase. Both peptides were found to be octapeptides; Led-CC-I has the primary structure pGlu-Val-Asn-Phe-Ser-Pro-Asn-Trp-NH2, and Led-CC-II has the primary sequence pGlu-Leu-Thr-Phe-Thr-Pro-Asn-Trp-NH2. These structures are identical to the two hypertrehalosaemic hormones from the American cockroach. Preliminary experiments show that the synthetic peptides are apparently involved in the control of amino acid metabolism during flight of the potato beetle.