[Low molecular weight peptides from the venom of the giant hornet Vespa orientalis. Structure and function].

Three 14-member linear peptides (HR-1, HR-2 and HR-3) capable of degranulating mast cells and thus initiating histamine release were isolated from the venom of the giant hornet Vespa orientalis, using reverse phase high performance liquid chromatography. The complete amino acid sequence of the peptides HR-1 and HR-2 molecules and partial structure of peptide HR-3 were determined, using automatic degradation by the Edman method. It was shown that peptide HR-1 at relatively low concentrations (2-20 micrograms/ml) selectively liberated histamine from rat mast cells and, when taken at higher doses (50-100 micrograms/ml), exerted a non-selective cytotoxic action. Besides, this peptide caused erythrocyte hemolysis, inhibited Ca2+-ATPase with concomitant uncoupling of Ca2+ transport and ATP hydrolysis as well as induced the conductance of lipid bilayer membranes, predominantly for monovalent cations due to the formation of nonspecific single permeability channels.