Biochemical characterization of lebetase, a direct-acting fibrinolytic enzyme from Vipera lebetina snake venom. 1998

J Siigur, and M Samel, and K Tõnismägi, and J Subbi, and E Siigur, and A T Tu
Institute of Chemical Physics and Biophysics, Tallinn, Estonia. siigur@kbfi.ee

Lebetase, the fibrinolytic enzyme isolated from Vipera lebetina (Levantine viper) snake venom is a metalloenzyme that contains one mole of Zn2+ and one mole of Ca2+ per mole of protein. Lebetase is inhibited by dithiothreitol, suggesting that disulfide bonds are necessary for holding the structure. Vipera lebetina venom contains several isoforms of lebetase in the interval of pI 4.6-5.4. Two lebetase fractions I (pI of the main component 5.0) and II (pI of the main component 5.3) degrade fibrin and fibrinogen by hydrolysis of the alpha and beta chains. The molecular weights of the cleavage products produced by the two different lebetase fractions are identical. The metal ions, Cd2+, Cu2+, Co2+, inhibit fibrinolytic and caseinolytic activity of lebetase I and II. Using mass spectrometry we characterized differences in molecular masses of lebetase I and II (22719 Da and 22912 Da). Vipera lebetina venom from a single snake contains mainly one form of lebetase. Lebetase I is more stable at low pH than lebetase II. The lebetases I and II inhibit platelet aggregation induced by ADP in a dose-dependent manner.

UI MeSH Term Description Entries
D008666 Metalloendopeptidases ENDOPEPTIDASES which use a metal such as ZINC in the catalytic mechanism. Metallo-Endoproteinases,Metalloendopeptidase
D008670 Metals Electropositive chemical elements characterized by ductility, malleability, luster, and conductance of heat and electricity. They can replace the hydrogen of an acid and form bases with hydroxyl radicals. (Grant & Hackh's Chemical Dictionary, 5th ed) Metal
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
D010974 Platelet Aggregation The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS. Aggregation, Platelet
D001792 Blood Platelets Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation. Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D003094 Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of SKIN; CONNECTIVE TISSUE; and the organic substance of bones (BONE AND BONES) and teeth (TOOTH). Avicon,Avitene,Collagen Felt,Collagen Fleece,Collagenfleece,Collastat,Dermodress,Microfibril Collagen Hemostat,Pangen,Zyderm,alpha-Collagen,Collagen Hemostat, Microfibril,alpha Collagen
D004795 Enzyme Stability The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat. Enzyme Stabilities,Stabilities, Enzyme,Stability, Enzyme
D005342 Fibrinolysis The natural enzymatic dissolution of FIBRIN. Fibrinolyses
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations

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