title: Conversion of fibrinogen to fibrin induced by preferential release of fibrinopeptide B.
abstract: Fibrin clot-promoting enzyme preferentially releasing fibrinopeptide B from fibrinogen was isolated from the crude venom of Agkistrodon contortrix and its mode of action was studied in detail. A purification procedure involving affinity chromatographies on immobilized lectin and arginine removed plasmin-like and kallikrein-like activities towards low-molecular-weight chromogenic substrates. Fibrin-promoting enzyme cleaved off only fibrinopeptides A and B from fibrinogen. The initial relative rate of release of fibrinopeptide B/fibrinopeptide A depended strongly on the presence of Ca2+. In the absence of Ca2+ the amount of fibrinopeptides released by fibrin-promoting enzyme at the gel point was greater. Fibrinopeptide B was no longer released before fibrinopeptide A from the non-polymerizing N-terminal disulphide knot of fibrinogen. Catalyzed by activated factor XIII, complete gamma-dimer and alpha-polymer formation was observed in fibrin from which only 23% of fibrinopeptide A, but 100% of fibrinopeptide B was released by fibrin-promoting enzyme. gamma-dimer formation markedly preceded alpha-polymer formation. These results strongly imply a similar overall arrangement of monomer molecules in this fibrin when compared with a thrombin-induced fibrin in which fibrinopeptide A is released before fibrinopeptide B. These observations support the concept that on fibrinopeptide B release from fibrinogen polymerization sites are exposed which reinforce the sites exposed on the release of fibrinopeptide A.
authors.affiliation: Institute of Hematology and Blood Transfusion, Prague, Czechoslovakia.
authors.forename: J E
authors.initials: JE
authors.lastname: Dyr
authors.forename: B
authors.initials: B
authors.lastname: Blombäck
authors.forename: B
authors.initials: B
authors.lastname: Hessel
authors.forename: F
authors.initials: F
authors.lastname: Kornalík
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D003435:Crotalid Venoms / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005176:Factor XIII / Q000378:metabolism; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005344:Fibrinopeptide A / Q000378:metabolism; D005345:Fibrinopeptide B / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D012697:Serine Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: C031442:Agkistrodon venoms; D003435:Crotalid Venoms; D046911:Macromolecular Substances; D005344:Fibrinopeptide A; D005345:Fibrinopeptide B; D005337:Fibrin; D005340:Fibrinogen; D005176:Factor XIII; D012697:Serine Endopeptidases; D002118:Calcium