The Direct Actinc α-Fibrin(Ogen)Olytic Enzymes from Snake Venoms

Abstract

A variety of α-fibrin(ogen)olytic enzymes have been found in snake venoms. More than 15 α-fibrin(ogen)ases have been isolated and characterized. Most work has been done with the venom of snakes belonging to a few species from the Agkistrodon, Crotalus, Trimeresurus, Bothrops, and Vipera. Only one α-fibrin(ogen)olytic enzyme is characterized from Elapidae snake venoms. The enzymatic properties of these proteinases are described in relation to action on fibrinogen, fibrin, and casein. The fibrinolytic enzymes act directly on fibrin and do not activate plasminogen. The proteolytic activity of these metalloproteinases is inhibited by EDTA. Most thoroughly investigated snake venom fibrinolytic enzymes are fibrolase from Agkistrodon contortrix contortrix venom, atroxase from Crotalus atrox venom and cerastase from Cerastes cerastes venom. Antibodies to fibrolase were prepared and their cross-reactions with other fibrinolytic components from several snake venoms have been detected. These antibodies were successfully used for purification of fibrolase from crude southern copperhead venom. Fibrolase and atroxase have no hemorrhagic activity, and they effectively solubilize artificial thrombi. Research in this area has a chance to provide new therapeutic agents for dissolving thrombi.