Le actions including coagulation [11,32,36,37]. These proteins may induce hemorrhage and capillary permeability disorders, through their disintegrin domain or related proteins that disrupt primary hemostasis by acting on platelet adhesion. Thus, a single molecule can be endowed with several activities. The structural differences between proteins, natural factors of hemostasis, 3 as well as the multiplicity of target components of the same venom, are elements that could explain the efficiency of partial immunotherapy [15]. Fibrinogenases (serine proteinases or metalloproteinases) are widespread in Viperidae venoms. They hydrolyze fibrinogen and/or degrade the fibrin clot, enhancing the effect of hemorrhagic metalloproteinases that give rise to pathological bleeding.Coagulant and fibrinogenolytic activities of isolated moleculesFibrinogen is a glycoprotein of 340 kDa with three polypeptide chains; A (67 kDa), B (50 kDa) and (43 kDa) linked by disulfide bonds. It can be hydrolyzed by thrombin, thus producing fibrin components and fibrinopeptides. Thrombin activity (control) on fibrinogen demonstrated the release of fibrinopeptide A (FpA) followed by fibrinopeptide B (FpB). Proteolytic enzymes of Cerastes cerastes venom were identified as , or fibrinogenases depending on their ability to hydrolyze the fibrinogen in vitro. SDS-PAGE analysis of fibrinogen in the presence of venom revealed two entities (55 kDa and 50 kDa) indicating activities of - 3-Amino-1H-indazole-4-carbonitrile and -fibrinogenase. Purification and characterization of three procoagulant proteinases (RP34, afa ytin and CC3-SPase proteinase) showed fibrinogenolytic activities when analyzed by SDS-PAGE, afa ytin and RP34 Boc-D-Lys-OH displayed, respectively, ,?fibrinogenase and -fibrinogenase activity [11,32,34]. Like afa ytin, CC3-SPase is also characterized as an ,-fibrinogenase due to the release of both A and B fibrinopeptides. Susceptibility of afa ytin to diisopropyl fluorophosphate and benzamidine indicates the presence of a serine and an aspartic (or glutamic) acid residues in the catalytic site. Calcium is required for structural cohesion of the afa ytin molecule [11]. CCSV-MPase cleaves only the B chain of fibrinogen and exerted no action on A or chains. This property contrasts with those of other SVMPs which preferentially cleave only the Afibrinogen chain. However, these metalloproteinases, belonging to the PI class of SVMPs, present low molecular mass, with only the metalloproteinase domain, as inthe case of fibrolase purified from Akgistrodon contortrix contortrix, piscivorase II of Akgistrodon piscivorus piscivorus, lebetase purified from the venom of Vipera lebetina, neuwiedase from Bothrops neuwiedi venom, the atroxase of Crotalus atrox and leucurolysins from venom of Bothrops leucurus [5,38-42]. Proteinases (afa ytin, RP34, CC3-SPase and CCSVMPase) showed caseinolytic activity as crude venom. CC3SPase displayed arginine ester hydrolase activity while the CCSV-MPase does not. Both molecules presented a high amidolytic activity similar to that of crude venom. Previous results revealed that the use of specific inhibitors for serine proteinases and metalloproteinases showed that CC3SPase is a thrombin-like Ca2+-dependent serine proteinase. PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/14445666 Afa ytin isolated from the venom of Cerastes PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/8833965 cerastes showed that Ca2+ is essential for its activity not only as a cofactor but can contribute to the stability or structural cohesion of the enzyme [11]. CCSV-MPase appears to be a zinc-dependent metalloproteinase given tha.