Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two radiochemical esterolytic assays for urokinase are described. One assay is based on the urokinase-dependent hydrolysis of Nalpha-acetyl-glycyl-L-lysine [3H]methyl ester and the other on the urokinase-dependent activation of plasminogen and assay of generated plasmin with Nalpha-tosyl-L-arginine [3H]methyl ester. The assays are performed in tubes placed in liquid scintillation counting vials. At the end of the experiment generated [3H]methanol is extracted into the liquid scintillation cocktail and counted. Unhydrolyzed substrate largely remains in the aqueous phase and contributes only a small fraction of the counts. This facile separation of 3H-labeled alcohol from the ester substrate allows the simple and highly sensitive assay for urokinase. The assays give results in good agreement with the classical fibrin plate assay.
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PMID:Sensitive radiochemical esterolytic assays for urokinase. 0 14

It has previously been shown, that large differences exist between the effects of 6-aminohexanoic acid or alpha1-antitrypsin on fibrinolysis caused by a porcine tissue plasminogen activator or by human urokinase, while insignificant differences exist between the effects of a number of natural protease inhibitors on fibrinolysis caused by the two types of plasminogen activator. The present study shows that changes in substrate composition (pH, ionic strength fibrinogen concentration, plasminogen concentration) may influence to different degrees the fibrinolytic activities of human urokinase and the porcine tissue plasminogen activator. It is suggested, that this finding is partly related to marked differences in affinity for fibrin of the two activators.
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PMID:Differences in the reactivities of human urokinase and the porcine tissue plasminogen activator. 1 58

A plasminogen activator secreted by cultured human pancreatic carcinoma (Mia PaCa-2) cells has been purified to apparent homogeneity by procedures including Sepharose-L-arginine methyl ester affinity chromatography, Sephadex G-200 gel filtration, isoelectric focusing, and sodium dodecyl sulfate gel electrophoresis. The plasminogen activator shares many properties with urokinase including: molecular weight (55 000), isoelectric point (8.7), heat stability (60 degrees C, 30 min), PH stability (1.5-10), and its mode of activation of plasminogen. The intracellular enzyme is membrane bound and can be solubilized by detergent. Solubilized activator has a molecular weight similar to that of the secreted enzyme as determined by sodium dodecyl sulfate gel electrophoresis. The production of plasminogen activator by Mia PaCa-2 cells is totally inhibited by actinomycin D and cycloheximide.
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PMID:Purification and characterization of a plasminogen activator secreted by cultured human pancreatic carcinoma cells. 1 90

Two plasminogen activators (1 and 2) were isolated from human seminal plasma by hiigh-speed centrifugation, Sephadex-gel filtration and ion-exchange chromatography. The activators were shown to be homogeneous by polyacrylamide-disc -gel electrophoresis at pH 8.3 and 4.5, and by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The molecular weights of activators 1 and 2 were estimated as 69 000 and 74 000. Their amino acid compositions are very similar, both being high in aspartic acid, glutamic acid, serine, glycine and leucine, and low in methionine, tryptophan, tyrosine, isoleucine and histidine. Activators 1 and 2 each possess 16 cysteine residues. Both activators have isoelectric points of approx. 7.0, are stable over a wide pH range at temperatures up to 60 degrees C, but lose activity at higher temperatures, particularly under very basic or acidic conditions. They are not inhibited by EDTA, Mg2+ and Ca2+ at 10 mM concentrations, but their activity decreases on addition of 10 mM-cysteine or Fe2+ and 6-aminohexanoate or sera from pregnant women. The precipitin band formed between urokinase and its antiserum is continuous with the precipitin bands formed between the seminal plasminogen activators and the urokinase antiserum. Antisera to urokinase inhibit both the activity of urokinase and the seminal plasminogen activators.
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PMID:Purification of plasminogen activators from human seminal plasma. 2 36

Thrombolytic therapy is aimed at dissolving thrombi. Streptokinase (SK) and urokinase (UK) are currently used in France but their mode of action has not been completely elucidated, which renders the establishment of therapeutic protocols and the choice of doses difficult. This treatment has a certain number of contraindications which must be strictly respected. The effectiveness of SK and UK in high doses has been demonstrated, in particular in pulmonary embolism and acute arterial obstruction of the limbs, but there is a risk of haemorrhage, whilst UK in moderate doses is usually well tolerated but has yet to prove its effectiveness in randomised double blind trials. Laboratory control has been simplified but it is essential not to forget the importance of clinical monytoring. Finally, drugs have recently been used in association with thrombolytics and more particularly the administration of plasminogen or defibrinating agents before or after thrombolytics.
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PMID:[Thrombolytic treatment (theoretical basis, therapeutic protocols, monitoring)]. 3 Nov 15

A fully carbamylated derivative of plasminogen having no free amino groups has been prepared and converted by urokinase to an active enzyme, called carbamyl plasmin A, with a single free NH2-terminal amino group (Val-561). Carbamyl plasmin A was shown to possess a catalytically essential ionizing group having pK 8.6. Carbamylation of the free NH2-terminal amino group of carbamyl plasmin A led to complete loss of catalytic activity. The results of solvent perturbation studies of normal plasmin (EC 3.4.21.7) indicate that the group with pK 8.4 is a neutral acid group. It is suggested that the catalytically essential ionizing group of plasmin having a pK of 8.4 is the alpha-ammonium group of the NH2-terminal Val-561 or the light chain of plasmin, forming an ion pair with a COO- group of an aspartate or glutamate residue.
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PMID:Studies on the nature of the catalytically essential ionizing group of plasmin with pK 8.4. 4 Jun 5

Four protease inhibitors have been identified in human serum and methods for their isolation are described. After removal of the euglobulin fraction, serum was submitted to ion exchange chromatography and gel filtration, and fractions were tested for inhibition of the lysis of plasminogen-deficient fibrin clots by plasmin, trypsin and elastase. In addition inhibitors of plasminogen activation were sought by studying the effects of separated fractions on the lysis of plasminogen-rich fibrin clots by urokinase. Examination by immunophoresis showed that three of the separated inhibitors were alpha2-macroglobulin, alpha1-antitrypsin and inter-alpha-trypsin inhibitor. The fourth antiprotease was a powerful inhibitor of both urokinase-induced and plasmin-induced clot lysis, and was identified as an inter-alpha-globulin from its electrophoretic mobility in agarose gels.
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PMID:Serum inhibitors in fibrinolysis. 5 65

Porcine plasmin (EC 3.4.21.7) is obtained from plasminogen activated by human urokinase. This enzyme can bind, in an equimolecular ratio, to an alpha2-macroglobulin isolated from porcine serum. The number of active sites of plasmin has been determined through a burst titration of nitroaniline during the presteady-state hydrolysis of an amide substrate (N-alpha-carbobenzoxy-L-arginine-p-nitroanilide). The kinetic constants relative to a very sensitive ester substrate (N-alpha-carbobenzoxy-L-lysine nitrophenylester) hydrolysis have been measured. The binding of plasmin to alpha2-macroglobulin results in a complete inhibition of proteolytic activity, a reduction of active sites number and a decrease of esterolytic activity towards this substrate. In the complex, the residual activity (about 60%) is protected from protein inhibitors. Absorbance difference spectra show that 1 mol of alpha2-macroglobulin binds 1 mol of plasmin and 2 mol of trypsin. When plasmin is first bound to alpha2-macroglobulin, only 1 mol of trypsin can gain access tothe second site without removing the plasmin, showing that a steric hindrance is implicated in the inhibition performed by alpha2-macroglobulin binding.
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PMID:[Study of the complex between porcine plasmin and alpha2-macroglobulin (author's transl)]. 5 8

"Hemorrhage in the newborn" has long been recognized as merely a result of vitamin K deficiency. However, it is also recognized that fibrinolysis, especially the correlation between the plasminogen-activator and plasmin-inhibitors, play an important role in this disease during the neonatal period. With this in mind, we compared thromboelastograms (TEG) from samples with and without urokinase (plasminogen-activator). In 13 out of 15 newborn infant blood-samples (prior to and after addition of urokinase) the thromboelastogram showed the pattern of a consumption coagulopathy. The change in the concentration of plasmin-inhibitor during the neonatal period was also measured using alpha2-macroglobulin, alpha1-antitrypsin and antithrombin III with M-partigen-plates. The value of alpha2-macroglobulin showed normal adult levels but the value of alpha1-antitrypsin and antithrombin III did not even reach half of the adult level. During the newborn period, the plasmin-inhibitor shows a remarkable lowering tendency and it may be surmised that with such a lowering tendency plasmin-inhibitor may constitute an exceptionally large handicap when the activator is working. This is especially true in the case of lung hemorrhage since the activator arises from a severe pathological state in the lungs and in addition because this is complicated by the lowering of plasmin-inhibitor. These results indicate that the low level of plasmin-inhibitors work synergistically with the high value of activator. The low level of antithrombin III could be the reason for coagulation disorders such as disseminated intravascular coagulation, (DIC).
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PMID:New neonatal problems of blood coagulation and fibrinolysis. I. The change of plasmin inhibitor levels in the newborn infant. 6 4

Two thrombolytic agents are mainly used in patients: streptokinase (SK) and urokinase (UK). UK from human origin is an endopeptidase which is able to convert plasminogen into plasmin. UK is only secreted by the kidney and is only found in urine which is presently the only source of extraction. Studies in man have shown that UK produces a highly reproducible state of enhanced plasma thrombolytic activity with a high fibrinolysis/fibrnogenolysis ratio and a lack of toxicity and antigenicity. The half life in Animal is short as well as the duration of fibrinolytic activity in Man. In clinical experience, positive results have been reported in pulminary embolism while the issues in myocardial infarction are controversial. Suggestive results have been registered in deep vein thrombosis, in ophthalmologic field and in desobstruction of arterio-venious shunts. No evident benefit has been noted in cerebral vascular disease. Up to now, UK has been very well tolerated.
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PMID:[Urokinase. Biochemical therapeutical and therapeutical data (author's transl)]. 6 58


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