FACTOR X ACTIVATING PROTEASES FROM SNAKE VENOMS

Abstract

A variety of factor X activators have been detected in snake venoms. About 10 activators have been isolated from Viperidae, Crotalidae, and Elapidae venoms. Viperidae and Crotalidae venom activators are mainly metalloproteases. Only two factor X activators are characterized from Elapidae venoms, both belonging to serine proteases. Most thoroughly investigated snake venom factor X activators are from Vipera russelli (now renamed Daboia russelli; RVV-X) and Vipera lebetina (now renamed Macrovipera lebetina; VLFXA). VLFXA is cloned and sequenced, and its primary structure is deduced from the cDNA sequence. Both activators consist of a heavy chain and two C-type lectin–like light chains that are held together by disulfide bonds. Primary stuctures of the heavy chain and one light chain are similar for both activators. The primary structure of the second light chain is not detected in RVV-X. Heavy chains of RVV-X and VLFXA contain metalloprotease and disintegrin-like and cysteine-rich domains. All chains of VLFXA are synthesized from different genes. The primary structures of factor X activating snake venom serine proteases remain unknown.

Keywords: :

• Factor X activator
• Metalloprotease
• C-type lectin-like protein
• cDNA cloning
• Snake venom
• Vipera russelli
• Vipera lebetina
• Bothrops atrox
• Cerastes cerastes
• Vipera aspis
• Vipera berus, MALDI-TOF MS
• LC-MS/MS.