Heparin with plasmin

Fig. 8. Kinetics of unstabilized fibrin hydrolysis with complexes of immobilized heparin with fibrinogen (1), thrombin (2), fibrinolysin (plasmin) (3), and serum albumin (4),06)...

The kinetics of the lytic effect displayed by the complexes of immobilized heparin with thrombin and fibrinogen, in distinction from those with plasmin, are described by their saturation curves. The observed slowing down of the dissolution of unstabilized fibrin is probably due to the inhibiton of the lytic activity of the complexes by the soluble products of the reaction. In fact, as it was shown in Ref. 106, further addition of immobilized heparin-protein complex to partially hydrolyzed fibrin results in a complete recovery of the dissolution rate. 

Tincture of the dried seed, on agar plate at a concentration of 30 p,L/disc, was inactive on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Extract of 10 g plant material in 100 mL ethanol was used b Anticoagulation activity. Serpin BSZx (an inhibitor of trypsin and chemotrypsin) inhibited thrombin, plasma kallikrein, factor Vlla/tissue factor, and factor Xa at heparin-independent association rates. Only factor Xa turned a significant fraction of BSZx over as substrate. Activated protein C and leukocyte elastase were slowly inhibited by BSZx, whereas factor Xlla, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein, and elastase were not or only weakly affected. Trypsin from Fusarium was not inhibited, while interaction with subtilisin Carlsberg and Novo was rapid, but most BSZx was cleaved as a substrate L... 

At present, the binary water-soluble preparation of heparin and proteolytic enzymes is being applied for the treatment of thromboses. For instance, injection into the bloodstream of heparin-plasmin complex or a heparin-plasmin-streptokinase preparation leads to the total dissolution of the thrombus, while if introduced separately, heparin and streptokinase do not display the lytic action at all, and plasmin, alone or together with streptokinase, dissolves the thrombus only partially 132>. The treatment of acute thrombophlebitis with trypsin resulted in a full dissolution of the thrombus and in an increase of antithrombin III in the blood 133). Administration of trypsin together with heparin has an effect similar in efficiency to the action of the heparin-plasmin complex 134>. The use of a mix of heparin and urokinase for improving tbrom-boresistance of polymeric materials was also described 13S). These substances were immobilized by preliminary coating of the surface of a polymer with a graphite layer and subsequent adsorption of heparin and the enzyme. 

Antithrombin III (AT-III), a single-chain glycoprotein of 58 kDa and 480 amino acids, is synthesized in the liver. It is a serine protease inhibitor, and acts as the most important inhibitor in the coagulation cascade to avoid blood clot formation. AT-III inhibits a wide spectram of serine proteases induding thrombin, factors IXa, Xa and XIa, kaUikrein, plasmin, urokinase, Cl-esterase, and trypsin. AT-III interacts with heparin by binding to specific sul-fated and non-sulfated monosaccharide units on heparin. The binding of AT-III to heparin enhances the inhibition of factors IXa, Xa, and thrombin. 

XII Hageman factor The first factor in the intrinsic pathway. A/, 74000 (bovine), 76000 (human). Single chain glycoprotein. Activated by plasmin, kallikrein and XII,. Inhibited by antithrombin III (inhibition accelerated by heparin). Cl esterase inhibitor and lima bean trypsin inhibitor. Activation of XII initiated by contact with abnormal surfaces. 

Heparin has been fluorescently labeUed in a manner that does not alter the functional properties of the polysaccharide. The labelled polysaccharide has been used in conjunction with fluorescence polarization spectroscopy to monitor the binding of heparin to the L-serine proteases thrombin, factor XIa, factor Xa, and plasmin. The stoicheiometry and dissociation constants of the interactions have been measured. The kinetics of inactivation of the four proteases by anti-thrombin as a function of heparin concentration have also been measured. Evidence shows that the direct binding of heparin to anti-thrombin is probably responsible for the polysaccharide-dependent acceleration of hemostatic enzyme-inhibitor reactions. 

Heparin-serotonin complexation to form an entity with anticoagulant activity and lytic activity different from that of plasmin with respect to the fact that it lysed unstabilized fibrin clots in the presence of EACA has been reported.93 Evidence of a protective action of vitamin C in deep vein thrombosis has also been reported.94... 

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