title: Proteases from Vipera lebetina venom affecting coagulation and fibrinolysis.
abstract: Our studies of the venom from the Levantine viper Vipera lebetina have demonstrated the existence of both coagulants and anticoagulants in the same venom. We showed that V. lebetina venom contains: (1) proteases that degrade fibrinogen, but not fibrin; (2) fibrinolytic enzyme (lebetase); (3) factor X activator (VLFXA); (4) factor V activator (VLFVA). Fibrinolytic enzyme and VLFXA are metalloproteases; the other studied enzymes are serine proteases. alpha-Fibrinogenase has no homolog among known serine proteases. Beta-fibrinogenase is a typical thermostable arginine esterase that hydrolyzes esters and amides of arginine and attacks the beta-chain of fibrinogen. Lebetase is a direct-acting fibrinolytic zinc metalloendopeptidase related in amino acid sequence to reprolysins. We used the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry technique for the recovery and identification of peptides released by protease hydrolysis and for the detection of human factor X cleavage products after VLFXA hydrolysis. VLFXA cleaves the Arg(52)-Ile(53 )bond in the heavy chain of human factor X and the Arg(226)-Val(227) bond in human factor IX precursor; VLFVA cleaves Arg(1545)-Ser(1546) in factor V.
authors.affiliation: National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia. siigur@kbfi.ee
authors.forename: J
authors.initials: J
authors.lastname: Siigur
authors.forename: A
authors.initials: A
authors.lastname: Aaspõllu
authors.forename: K
authors.initials: K
authors.lastname: Tõnismägi
authors.forename: K
authors.initials: K
authors.lastname: Trummal
authors.forename: M
authors.initials: M
authors.lastname: Samel
authors.forename: H
authors.initials: H
authors.lastname: Vija
authors.forename: J
authors.initials: J
authors.lastname: Subbi
authors.forename: E
authors.initials: E
authors.lastname: Siigur
mesh_terms: D000818:Animals; D001665:Binding Sites; D001777:Blood Coagulation / Q000187:drug effects; D003029:Coagulants / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D005165:Factor V / Q000378:metabolism; D005170:Factor X / Q000378:metabolism; D005342:Fibrinolysis / Q000187:drug effects; D006801:Humans; D008666:Metalloendopeptidases / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D010447:Peptide Hydrolases; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014757:Viper Venoms / Q000032:analysis / Q000737:chemistry / Q000201:enzymology* / Q000378:metabolism
chemical_list: D003029:Coagulants; D010446:Peptide Fragments; D014757:Viper Venoms; D005165:Factor V; D005170:Factor X; D010447:Peptide Hydrolases; C121422:factor V activating enzyme; D008666:Metalloendopeptidases; C476774:factor X activator, Vipera lebetina