Capillary permeability-increasing enzyme-2 from the venom of Agkistrodon caliginosus (kankoku-mamushi): activity resulting from the release of peptides from fibrinogen.

When a mixture of the purified capillary permeability-increasing enzyme-2 from agkistrodon caliginosus venom and rabbit plasma was injected into the depilated skin of the back of rabbits, the capillary permeability-increasing activity was much greater than that induced by injection of the enzyme alone. To isolate the active substance, the mixture was subjected to reversed-phase high-performance liquid chromatography. Among the active peptides, five peptides were purified and their amino acid sequences were analyzed. These peptides were derived from the amino-terminal portion of the B beta-chain of fibrinogen. After the enzyme was incubated with rabbit fibrinogen, the three peptides were purified from the incubation mixture by high-performance liquid chromatography, and their amino acid compositions and amino acid sequences were determined. From these results, it was determined the peptides were derived from the amino-terminal portion of the B beta-chain of fibrinogen. This result indicates that the increase in capillary permeability induced by the enzyme is due to the peptides released from rabbit fibrinogen.