Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 1933 Streptokinase (SK) was isolated from bacterial strains of haemolytic Streptococci. Since then it has become the widest spread drug for fibrinolysis. SK, a protein, consists of 415 aminoacids and has a molecular weight of 47,000u. Together with the plasminogen (PLG) of the blood it forms activator complexes, which then convert other PLG molecules of the blood to plasmin. Plasmin attacks and dissolves fibrin deposits. As a substance produced by bacteria SK stimulates antibody formation in the body, the titer will increase during therapy, and SK lysis should be terminated after 6 days of treatment. Usually SK is administered intravascularly to treat a wide range of diseases, associated with pathological activation of hemostasis, like deep vein thrombosis, pulmonary embolism, myocardial infarction etc.. Contraindications can be traced back to the effects of SK on coagulation and the immune system. Bleeding is the most common side effect, but also a few anaphylactic reactions, caused by massive antigen-antibody precipitation have been observed. The rate of lethality of the treatment was established at 0.7% of the cases. To reduce the incidence of side effects modifications of the drug have been proposed, such as activator complex, light B chain SK, and acylated activator therapy. Compared with Urokinase, SK shows a higher rate of side effects, especially in the field of the immune system. Therapy with Urokinase can be controlled more easily. Nevertheless because of considerable price differences and logistics, SK is preferred in Europe and the USA. If strict guidelines in therapeutic use are followed, the rate of side effects of the drug can be curtailed and will be comparable to those of Urokinase.
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PMID:Review and current status of thrombolytic therapy with streptokinase. 354 44

Activation of Glu-plasminogen by single-chain urokinase-type plasminogen activator (sc-uPA), isolated from human urine, was studied in a purified system in the absence and presence of the cyanogen bromide fibrinogen fragment, FCB 2, and compared to plasminogen activation by two-chain high-Mr urokinase. Plasminogen activation by sc-uPA was significantly increased by the FCB-2 fibrinogen fragment, an effect brought about by decrease of apparent Km and increase of apparent kcat. During the course of plasminogen activation by scu-PA, two-chain urokinase was formed from 125I-sc-uPA to a significant degree only when a concentration of 30 nM plasmin was reached in the incubation mixture; this was only the case in the system stimulated by FCB-2 fibrinogen fragment and only after 30 min. Formation of two-chain urokinase was not, however, related to the increase in the rate of plasmin formation induced by the FCB-2 fibrinogen fragment.
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PMID:Effect of the cyanogen-bromide-2 fragment of fibrinogen on plasminogen activation by single-chain urokinase-type plasminogen activator. 360 16

The objectives of thrombolytic therapy in acute myocardial infarction are to restore coronary artery patency, salvage myocardium, reduce infarct size, and facilitate coronary artery repair. Urokinase and streptokinase are the two most frequently used thrombolytic agents. Both dissolve thrombi by converting circulating plasminogen, an inert precursor, into plasmin. One possible advantage of urokinase and streptokinase over new clot-specific agents is that the former have systemic fibrinolytic effects. This reduces blood viscosity and prevents other thrombi from forming. Angiography is the most objective technique for assessing reestablished arterial patency, but being invasive, it present disadvantages. Noninvasive criteria for coronary reperfusion include lowering of elevated ST-segments, shifting creatine kinase isoenzyme MB curves, and the appearance of reperfusion arrhythmias. Techniques for assessing myocardial salvage include thallium uptake, assessment of wall motion and myocardial thickening, ejection fraction, and positron emission tomography to assess infarct size. The role and appropriate timing of coronary artery repair after thrombolytic therapy are being studied.
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PMID:Objectives of thrombolytic therapy in acute myocardial infarction. 363 Nov 13

Lysis of fibrin in tissue culture has been shown to be due to plasminogen activator identified immunologically as urokinase. The present study examines fibrinolytic events in culture, particularly mechanisms leading to increased urokinase levels and accelerated fibrinolysis. Deposition of fibrin on cells in culture was followed by a two- to six-fold increase in urokinase in the supernates and rapid disappearance of the fibrin. Investigation of factors that might be responsible for these events (including fibrin, fibrinogen, vasoactive stimuli, and the enzymes thrombin and plasmin) indicated that the enhanced urokinase yields were mediated through plasmin and thrombin. Study of the possible modes of action of thrombin and plasmin indicated that these enzymes are capable of acting on the cells themselves as well as on cell-produced material. The effect on cells was manifested by mitotic activity or, occasionally, cell injury and death. Although these effects influenced urokinase levels, enhanced yields were explained best by the action of enzymes on cellproduced material. Studies with plasmin and thrombin, and also trypsin, indicated that proteolytic enzymes may act in various ways-affect the stability of urokinase, interfere with inhibition of urokinase by naturally occurring inhibitor(s), and induce urokinase activity from inactive material. Plasma and thrombin appeared to act primarily through the latter mechanism. Inactive material, which gave rise to urokinase upon exposure to proteolytic enzymes and which may represent urokinase precursor, was found in cultures of kidney, lung, spleen, and thyroid. Urokinase in such inactive state appears to be readily accessible to activation by enzymes, particularly plasmin and thrombin, thus facilitating removal of fibrin and possibly also providing pathways to excessive fibrinolysis.
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PMID:Increased plasminogen activator (urokinase) in tissue culture after fibrin deposition. 426 21

Urokinase-activated human plasma was studied by gel electrophoresis, gel filtration, crossed immunoelectrophoresis and electroimmunoassay with specific antibodies and by assay of esterase and protease activity of isolated fractions. Urokinase induced the formation of different components with plasminogen+plasmin antigenicity. At low concentrations of urokinase, a component with a K(D) value of 0.18 by gel filtration and post beta(1) mobility by gel electrophoresis was detected. The isolated component had no enzyme or plasminogen activity. In this plasma sample fibrinogen was not degraded for 10h, but when fibrin was formed, by addition of thrombin, fibrin was quickly lysed, and simultaneously a component with a K(D) value of 0 and alpha(2) mobility appeared, which was probably plasmin in a complex with alpha(2) macroglobulin. This complex showed both esterase and protease activity. After gel filtration with lysine buffer of the clotted and lysed plasma another two components were observed with about the same K(D) value by gel filtration as plasminogen (0.35), but beta(1) and gamma mobilities by gel electrophoresis. They appeared to be modified plasminogen molecules, and possibly plasmin with gamma mobility. Similar processes occurred without fibrin at higher urokinase concentrations. Here a relatively slow degradation of fibrinogen was correlated to the appearance of the plasmin-alpha(2) macroglobulin complex. The fibrin surface appeared to catalyse the ultimate production of active plasmin with a subsequent preferential degradation of fibrin and the formation of a plasmin-alpha(2) macroglobulin complex. The gel filtration and electrophoresis of the plasma protease inhibitors, alpha(1) antitrypsin, inter-alpha-inhibitor, antithrombin III, and C(1)-esterase inhibitor indicated that any complex between plasmin and these inhibitors was completely dissociated. The beta(1) and post beta(1) components appear to lack correlates among components occurring in purified preparations of plasminogen and plasmin.
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PMID:Different molecular forms of plasminogen and plasmin produced by urokinase in human plasma and their relation to protease inhibitors and lysis of fibrinogen and fibrin. 428 70

Urokinase-activated human plasma was analysed by acetic acid/urea/polyacrylamide-gel electrophoresis. The bands representing plasminogen, the plasmin-alpha 2-plasmin inhibitor and plasmin-alpha 2-macroglobulin complexes were identified by immunoprecipitation with specific antibodies and by comparison with purified components. Plasminogen and the plasmin-inhibitor complexes were isolated from plasma or thrombin-clotted plasma containing 125I-labelled Glu-plasminogen (residues 1-790) and urokinase. The plasma was kept at 37 degrees C for 0.5 and 10 times the lysis time of the clotted plasma, the clotted plasma until lysis. The plasmin heavy chain from the plasmin-inhibitor complexes was subsequently prepared. Only in one case could a low-grade proteolytic conversion of Glu- forms into Lys/Met/Val-forms (residues 77-790, 68-790 and 78-790 respectively) during the preparations be detected. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and N-terminal sequence analysis of the purified plasminogen and plasmin heavy chain showed the following. The plasminogen in plasma was on the Glu- form. Glu-plasmin constituted 0.74 and 0.58 of the plasmin bound to the alpha 2-plasmin inhibitor in plasma after brief and prolonged activation respectively. The rest was Lys/Met/Val-plasmin. The clotted plasma contained about equal amounts of Glu-plasminogen and Lys/Met/Val-plasminogen, and predominantly Lys/Met/Val-plasmin complexed to alpha 2-plasmin inhibitor and alpha 2-macroglobulin. The results of the analysis of the purified material substantiated the identity of radioactive protein bands in the gel after acetic acid/urea/polyacrylamide-gel electrophoresis.
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PMID:Identification of molecular forms of plasminogen and plasmin-inhibitor complexes in urokinase-activated human plasma. 620 93

Two urokinase preparations of different molecular weights were standardized against the International Reference Preparation for Urokinase and compared in an in vitro whole blood perfusion system using thrombi formed with whole blood and 125I-fibrinogen. Plasminogen was added to one group and normal saline to the other. Thrombolysis, as well as plasminogen and plasmin inhibitor levels were monitored over a 60 minute period following the addition of the urokinase to the perfusion mediums. There was a high correlation as well as no significant difference found between the percents lysis caused by the high and low molecular weight urokinase. Added plasminogen resulted in a rapid decrease of plasmin inhibitors in both urokinase groups. In the saline groups this decrease was highly negatively correlated with the percent lysis. It is concluded that both high and low molecular weight urokinase behave similarly in an in vitro whole blood thrombolytic perfusion system over the time period studied.
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PMID:Comparative study of thrombolysis by high and low molecular weight urokinase in an in vitro perfusion system. 622 33

A proteinase which can activate human, dog and rat plasminogen to plasmin has been isolated from the urine of female rats, using affinity chromatography on benzamidine-coupled Sepharose. Inhibition by diisopropylfluorophosphate, tosyl-L-lysine chloromethylketone and benzamidine classified the enzyme as trypsin-like. The proteinase has weak activity on alpha-casein and hemoglobin, but will not lyse fibrin clots. It readily cleaves arginyl amides, including synthetic substrates specific for human glandular kallikrein and other serine proteinases. A chromogenic substrate for human urokinase (pyro Glu-Gly-Arg-pNA) is a poor substrate for the rat proteinase. Characteristics of the enzyme, such as its molecular weight (25 900), kinetic parameters and inhibition by aprotinin, indicate that this proteinase is esterase A, described by several investigators. Esterase A is shown not to be a true urinary plasminogen activator but rather is a unique arginine-specific proteinase. Urokinase-like and kallikrein-like activity are part of a broader proteolytic activity displayed by this enzyme.
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PMID:Esterase A is a proteinase from rat urine that can activate plasminogen. 623 43

Thrombolytic therapy with Urokinase (UK) has often been successful but it is very difficult to determine the effective dosage of UK. It is reported that after UK administration, plasmin fibrinolytic activity was immediately inhibited by alpha 2-Plasmin inhibitor (alpha 2-PI). In this study, we used UK on patients with myoma to prevent the occurrence of thrombosis after operation and the initial decrease in alpha 2-PI activities following UK administration was investigated to determine the minimum effective dosage of UK required to suppress alpha 2-PI. An attempt was also made to measure UK activity in blood by means of chromogenic substrate S-2444, and in some cases by administering 60,000 I.U. UK, alpha 1-Antitrypsin (alpha 1-AT), alpha 2-Macroglobulin (alpha 2-M), Antithrombin III (AT III) and Plasminogen (Plg) were measured at the same time. The results were as follows: 1) By the drip infusion method. In all doses, alpha 2-PI and UK activity showed no remarkable change. 2) By the one shot method. a) A decrease in alpha 2-PI was observed following both 48,000 and 60,000 I.U. UK administration. It was noted that in the case of 48,000 I.U. UK, alpha 2-PI showed the lowest level, 60% of the pre-administration level. b) UK activity showed a gradual increase in the case of 60,000 I.U. UK only and large changes in the other cases. c) alpha 1-AT, alpha 2-M, AT III and Plg produced no remarkable changes. This indicated that the effective dosage of UK for suppressing alpha 2-PI was at least 48,000 I.U. UK with the one shot method, and alpha 2-PI is a reliable indicator of the effectiveness of UK therapy.
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PMID:[The changes of alpha 2-plasmin inhibitor, and notably urokinase activities in blood measured by synthetic chromogenic substrates S-2444 after urokinase administration]. 633 34

The plasminogen activator (PA) produced by freshly purified human monocytes-macrophages and histiocytic, lymphoma-derived U 937 cells was analyzed by zymography after sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and found to migrate with an apparent Mr of 55,000, identical to that of urokinase (Uk). By immunoprecipitation with antibodies specific for the two different types of PA, the enzyme was shown to be immunologically related to urokinase, and not to tissue PA. Urokinase was secreted in the form of the inactive Mr 55,000 zymogen prourokinase , and could be converted to the active Mr 55,000 enzyme by limited proteolysis with plasmin. Conditioned media from cultures of U 937 cells and monocytes-macrophages inhibited the fibrinolytic activity of exogenously added urokinase. Using [125I]-labeled urokinase we observed the formation of an enzyme-ligand complex, which was not dissociated by boiling in SDS and migrated with an apparent Mr 40,000 daltons higher than the free enzyme; since complexed urokinase was functionally inactivated as a PA, the ligand is an inhibitor of urokinase. This inhibitor is different from fibroblast-produced protease- nexin , in that it did not interact with thrombin. These results suggest that plasminogen activation by mononuclear phagocytes can be modulated through the secretion of both (pro)enzyme and a specific inhibitor.
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PMID:Concomitant secretion of prourokinase and of a plasminogen activator-specific inhibitor by cultured human monocytes-macrophages. 637 11


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