ISOLATION AND IDENTIFICATION OF AKH RPCH FAMILY PEPTIDES IN BLISTER BEETLES (MELOIDAE)/

Two peptides were isolated from methanolic extracts of corpora cardiac a of the blister beetle, Decapotoma lunata, by a single-step purificat ion procedure, utilizing C-18 reversed-phase high-performance liquid c hromatography (RP-HPLC) for separation, and the increase of haemolymph lipids in Locusta migratoria for bioassay. The native peptides were a nalysed by matrix-assisted laser-desorption ionization mass spectromet ry revealing main ions at m/z 1180 and 1009 respectively which were at tributed to the [M + Na](+) form of the respective peptides. After deb locking of the N-terminal pyroglutamate residue of each peptide, the s tructures of the deblocked peptides were determined by pulsed-liquid p hase sequencing employing Edman chemistry. The sequences of the two pe ptides, (1) pGlu-Leu-Asn-Phe-Ser-Pro-Asn-Trp-Gly-AsnNH(2) and (2) pGlu -Leu-Asn-Phe-Ser-Pro-Asn-TrpNH(2), characterize them as deca- and octa peptide members of the AKH/RPCH family. Whereas the decapeptide is a n ovel member of this family and is given the acronym Del-CC (Decapotoma lunata corpus cardiacum peptide), the octapeptide has previously been found in tenebrionid beetles and has the acronym Tem-HrTH. The corpor a cardiaca of two other species of blister beetles (Cyaneolytta pector alis and Mylabris coeca) contain the same two peptides as D. lunata, a s judged by RP-HPLC and biological activity. Neither a corpus cardiacu m extract of Decapotoma lunata nor the synthetic peptides Del-CC and T em-HrTH were active in mobilizing carbohydrates or lipids in the blist er beetle.