[Hemolytic effect of phospholipase A2 and orientotoxin from venom of the great hornet, Vespa orientalis].

The effect of toxic phospholipase A2 and orientotoxin from the venom of the giant hornet Vespa orientalis on human erythrocytes was studied. It was shown that these venom components are potent hemolytic agents, the efficiency of the latter being by about two orders of magnitude as high as that of phospholipase A2. The hemolytic function of the both components is enhanced in the presence of low concentrations of Ca2+, whereas high concentrations of this cation exert an inhibiting action.

[Determination of phospholipase A2 and lysophospholipase A1 in a mixture].

The phospholipase A2 and lysophospholipase A1 activities were determined in various mixtures. When estimating the phospholipase A2 activity in venoms of snakes and insects the known methods based on measuring a change in the optical density of the egg yolk suspension are not acceptible if in investigated object besides phospholipases lysophospholipases are present (venoms of viper and giant hornet). In this case anomalous curves of changes in the system optical density in time are obtained.

[Isolation and purification of two lipolytic enzymes from Vespa orientalis venom].

Two lipolytic enzymes--phospholipase A2 and lysophospholipase A1 were isolated in individual state from the venom of the big hornet Vespa orientalis. It was shown that these enzymes have approximately the same molecular weight of about 26 000, but differ in their electrophoretic mobilities. Besides, the enzymes possess marked specificity to lecithin and L-lysolecithin, respectively.

[Characterization of some membrane-active components of Vespa orientalis venom].

The molecular weight distribution of the components of giant hornet (Vespa orientalis) venom was studied, using gel-filtration on a column with Sephadex G-50. The effects of the venom and its constituent fractions on the permeability and stability of artificial bilayer phospholipid membranes, potassium ions release from the erythrocytes and mitochondrial oxidative phosphorylation parameters, as well as on the activity and stability of polyenzymic systems of the mitochondrial respiratroy chain, were studied. The data obtained suggest that the high molecular weight fractions contain phospholipases, whose activities are much higher than those of presently known venoms.