Isolation of the hypertrehalosaemic factors I and II from the corpus cardiacum of the Indian stick insect, Carausius morosus, by reversed-phase high-performance liquid chromatography, and amino-acid composition of factor II

Abstract

The separation of two peptides with hypertrehalosaemic activity from the corpus cardiacum of the Indian stick insect, Carausius morosus, was achieved by reversed-phase high-performance liquid chromatography using a Nucleosil C-18 column with a trifluoroacetic acid/acetonitrile gradient. The eluant was monitored at 210 nm and the hypertrehalosaemic activity was detected in ligated stick insects using a bioassay. In addition, the isolated material was potent in causing hyperlipaemia in migratory locusts and also in raising blood carbohydrates in the American cockroach. The amino-acid composition of the major peptide, hypertrehalosaemic factor II, was determined after acid hydrolysis with HCl or methanesulfonic acid. The analyses suggest that factor II is a nonapeptide which contains the following amino-acid residues: Asp, 2 Thr, Glu, Pro, Gly, Leu, Phe and Trp. This composition is almost identical to that of locust adipokinetic hormone I, lacking only one Asp residue.