Capillary permeability-increasing enzyme from the venom of Agkistrodon caliginosus (kankoku-mamushi): activity due to the release of peptide material from a protein in bovine plasma.

When a mixture of the purified capillary permeability-increasing enzyme from A. caliginosus venom and bovine plasma or heated bovine plasma was injected into the depilated skin of the back of a rabbit, the capillary permeability-increasing activity was much greater than that induced by injection of the enzyme alone. The substance which increases capillary permeability was extracted from the incubated mixture of bovine plasma and enzyme with 50-70% ethanol. Its activity was lost when treated with carboxypeptidase A. Thus, it is supposed that the increase in capillary permeability induced by the enzyme is due to a low molecular weight peptide released from a protein in bovine plasma by the action of the enzyme. No liberation by the enzyme of histamine or anaphylatoxins of the complement system was found.