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

The effects of various concentrations of plasmin and activated protein C on the factor VIII procoagulant activity (VIII:C) and coagulant antigen (VIII:CAg) were studied in factor VIII concentrates and normal plasma. Small amounts (0.1 CTA U/ml) of plasmin rapidly destroyed VIII:C, and affected, but did not destroy VIII:CAg, in factor VIII concentrates. In normal plasma larger amounts of plasmin (1.8 CTA U/ml) was required to inactivate VIII:C in order to exceed the neutralizing capacity of alpha 2-antiplasmin. VIII:CAg was unchanged indicating a limited proteolysis. The difference between VIII:C and VIII:CAg was found also in urokinase-activated plasma. Activated protein C (5 micrograms/ml), in the presence of Ca2+ and phospholipids, inactivated VIII:C without affecting VIII:CAg in a high purity factor VIII concentrate. Higher concentrations of activated protein C (25 micrograms/ml) caused a slight decrease of VIII:CAg, even in the absence of Ca2+ and phospholipids, but did not change VIII:CAg in normal plasma or serum.
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PMID:The effects of plasmin and protein Ca on factor VIII:C and VIII:CAg. 622 18

Tripeptide derivatives of lysyl or arginyl chloromethylketone inhibit the trypsin-like serine proteases trypsin, thrombin, plasmin, Factor Xa, urokinase, tissue-type plasminogen activator and protein Ca following the reaction scheme: (formula; see text) Extremely potent tripeptide inhibitors were obtained for thrombin and trypsin (k2/Ki greater than 10(6) M-1s-1), moderate inhibitors for plasmin and Factor Xa (10(6) M-1s-1 greater than k2/Ki greater than 10(4) M-1s-1) and only weak inhibitors for urokinase, tissue-type plasminogen activator and protein Ca (k2/Ki less than 10(4) M-1s-1). Thrombin and Factor Xa as well as urokinase and tissue-type plasminogen activator can be discriminated on the basis of their inhibitory spectrum towards some of these inhibitors.
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PMID:Inhibition of trypsin-like serine proteinases by tripeptide arginyl and lysyl chloromethylketones. 623 78

Protein C inhibitor isolated from human plasma inhibited thrombin, factor Xa, trypsin and chymotrypsin as well as activated protein C, but had very little effect on urokinase and plasmin. The inhibition constants (K1) of protein C inhibitor for activated protein C, thrombin and factor Xa were 5.6 X 10(-8) M, 6.7 X 10(-8) M and 3.1 X 10(-7) M, respectively. The second-order rate constant for inhibition of activated protein C by the inhibitor increased about 30-fold in the presence of an optimal heparin concentration (5-10 units/ml). The inhibition of activated protein C by plasma protein C inhibitor was also accelerated by heparin. When activated protein C (Mr = 62,000) was incubated with protein C inhibitor (Mr = 57,000), enzyme-inhibitor complexes with apparent Mr = 102,000 and 88,000 were observed in the nonreduced and the reduced samples, respectively, on SDS-polyacrylamide gel electrophoresis. In addition to these complexes, a band of unbound enzyme and a band with Mr = 54,000 were detected. When 125I-labeled protein C inhibitor was exposed to activated protein C, the inhibitor band was converted to bands with apparent Mr = 102,000 and 54,000 in the nonreduced samples, as determined by autoradiography after gel electrophoresis in SDS. The band with Mr = 54,000 also appeared when the inhibitor reacted with other serine proteases. The activated protein C was released from the inactive complex by treatment with 1 M ammonia or hydroxylamine. This phenomenon was found by SDS-polyacrylamide gel electrophoresis to represent the dissociation of the enzyme-inhibitor complex by ammonia or hydroxylamine into the free enzyme and the proteolytically modified inhibitor.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanism of inhibition of activated protein C by protein C inhibitor. 632 92

The effect of orally-administered stanozolol, 5 mg b.d. on fibrinolysis, coagulation and on various haematological and biochemical parameters have been studied in 16 healthy adults, 8 males and 8 females. Statistically significant enhancement of extrinsic (tissue-type) plasminogen activator activity was detected in all subjects studied. This was associated with significant increases in plasma plasminogen and a concomitant reduction in histidine-rich glycoprotein. There were no changes in plasma urokinase activity. Changes in the coagulation system included significant reduction in plasma fibrinogen and elevation of protein C and antithrombin III. Changes in plasma lipids included significant reduction of HDL cholesterol associated with an increase in LDL triglycerides. No change occurred in total cholesterol. There were no major differences between the sexes, nor were there serious side effects. The effects of stanozolol on extrinsic (tissue-type) plasminogen activator activity, "free" plasminogen, protein C and antithrombin III, argue strongly in favour of its therapeutic potential.
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PMID:Stanozolol-induced changes in fibrinolysis and coagulation in healthy adults. 674 May 47

The human intracellular serine proteinase inhibitor, proteinase inhibitor 6 (PI-6), was expressed in the methylotropic yeast Pichia pastoris. The PI-6 cDNA was modified to encode six histidine residues immediately after the initiation codon, and was placed under the control of the P. pastoris alcohol oxidase promoter in the vector pHIL-D2. On the methanol induction, active recombinant PI-6 was produced within the yeast cells, and following cell lysis, was separated from yeast proteins by affinity chromatography using nickel nitrilo-tri-acetic acid (NTA) resin. The interaction of recombinant PI-6 with a range of serine proteinases was studied. Second order association rate constants (ka) were derived for the interaction with trypsin (1.8 x 10(6) M-1 s-1), thrombin (1.2 x 10(5) M-1 s-1), urokinase plasminogen activator (4.0 x 10(4) M-1 s-1), plasmin (1.3 x 10(6) M-1 s-1), and activated protein C (7.5 x 10(3) M-1 s-1). By monitoring complex formation, recombinant PI-6 was also shown to interact with factor Xa. No complex formation was observed with chymotrypsin, human leukocyte elastase, cathepsin G and tissue plasminogen activator, although PI-6 is apparently a substrate for chymotrypsin, leukocyte elastase and cathepsin G.
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PMID:Production and characterization of recombinant human proteinase inhibitor 6 expressed in Pichia pastoris. 754 63

The quest continues for thrombolytic agents with a higher thrombolytic potency, specific thrombolytic activity and/or a better fibrin selectivity. Several lines of research towards improvement of thrombolytic agents are being explored, including the construction of mutants and variants of plasminogen activators (PAs), chimaeric PAs, conjugates of PAs with monoclonal antibodies, and PAs from animal or bacterial origin. Some of these new thrombolytic agents have shown promise in animal models of venous or arterial thrombosis and in pilot clinical studies. Such molecules include numerous mutants of tissue-type PA (t-PA) with prolonged in vivo half-life and/or resistance to protease inhibitors, and chimaeric PAs consisting of different regions of t-PA and of urokinase-type PA (u-PA). Several molecular forms of the thrombolytic substance in the saliva of the vampire bat have been characterised and cloned. Vampire bat PA exhibits 85% homology to human t-PA but lacks kringle 2 and the plasmin-sensitive cleavage site. A thrombolytic enzyme of 203 amino acids is present in the venom of a southern copperhead snake. This polypeptide, termed fibrolase, is now produced by recombinant technology. Fibrolase does not activate plasminogen or protein C, but directly degrades the alpha and beta chains of fibrin and fibrinogen. Recombinant staphylokinase is not an enzyme, but it forms a 1:1 stoichiometric complex with plasminogen, which becomes active after conversion of plasminogen to plasmin. It is a potent and highly fibrin specific thrombolytic agent in animals and patients.
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PMID:Thrombolytic agents in development. 758 87

A novel plasminogen activator from Trimeresurus stejnegeri venom (TSV-PA) has been identified and purified to homogeneity. It is a single chain glycoprotein with an apparent molecular weight of 33,000 and an isoelectric point of pH 5.2. It specifically activates plasminogen through an enzymatic reaction. The activation of human native Glu-plasminogen by TSV-PA is due to a single cleavage of the molecule at the peptide bond Arg561-Val562. Purified TSV-PA, which catalyzes the hydrolysis of several tripeptide p-nitroanilide substrates, does not activate nor degrade prothrombin, factor X, or protein C and does not clot fibrinogen nor show fibrino(geno)lytic activity in the absence of plasminogen. The activity of TSV-PA was readily inhibited by phenylmethanesulfonyl fluoride and by p-nitrophenyl-p-guanidinobenzoate. Oligonucleotide primers designed on the basis of the N-terminal and the internal peptide sequences of TSV-PA were used for the amplification of cDNA fragments by polymerase chain reaction. This allowed the cloning of a full-length cDNA encoding TSV-PA from a cDNA library prepared from the venom glands. The deduced complete amino acid sequence of TSV-PA indicates that the mature TSV-PA protein is composed of 234 amino acids and contains a single potential N-glycosylation site at Asn161. The sequence of TSV-PA exhibits a high degree of sequence identity with other snake venom proteases: 66% with the protein C activator from Agkistrodon contortrix contortrix venom, 63% with batroxobin, and 60% with the factor V activator from Russell's viper venom. On the other hand, TSV-PA shows only 21-23% sequence similarity with the catalytic domains of u-PA and t-PA. Furthermore, TSV-PA lacks the sequence site that has been demonstrated to be responsible for the interaction of t-PA (KHRR) and u-PA (RRHR) with plasminogen activator inhibitor type 1.
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PMID:A novel plasminogen activator from snake venom. Purification, characterization, and molecular cloning. 773 Mar 29

Z-D-Phe-Pro-boroMpg-OPin (9a)1,2 has been shown previously to be a highly specific inhibitor of thrombin in spite of lacking an arginine-like guanidino group at the P1 site. A range of compounds have been synthesized based upon this lead compound, varying the neutral side chain at the P1 site. Of the 20 examples based upon the structures at P2 and P3 of Z-D-X-Pro (X being Phe or beta,beta-diphenylalanine), all were found to be effective inhibitors of thrombin (Ki's between 10 and 100 nM). Furthermore all exhibited a high specificity toward thrombin having values for a Ki(trypsin)/Ki(thrombin) ratio of between 10- and 100-fold. High ratio values were found for a number of the compounds tested against a range of serine proteinases (plasmin, factor Xa, kallikrein, urokinase, protein Ca, chymotrypsin, elastase, and cathepsin G). As far as potency toward thrombin, compounds containing the methoxypropyl group at P1 were favored over those with a methoxy grouping on a shorter alkyl chain (8) or without the methoxy group (1-5). The compounds display potent anticoagulant activity with values for 18 in thrombin time of 0.63 microM and in activated partial thromboplastin time of 2.0 microM. 11B NMR has been used to confirm interaction of the boron atom with the active site. From the high specificity shown with all the compounds we propose that the compounds, constitute a new class of thrombin inhibitors.
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PMID:Characterization of a class of peptide boronates with neutral P1 side chains as highly selective inhibitors of thrombin. 773 10

Snake venoms, especially from the Crotalidae family, contain a variety of enzymes that prevent blood coagulation by virtue of their fibrinolytic enzymes. Nineteen snake venoms were screened for fibrinolytic activity and the highest activity was found in the venom of Crotalus basiliscus basiliscus venom. The active principle, basilase, was isolated, purified, and found to have fibrinolytic and fibrinogenolytic activity. It had a molecular weight of 22,000 and 1 mol of zinc per mole of protein associated with it. The proteolytic activity of the enzyme against dimethyl casein was inhibited by ethylenediaminetetraacetic acid and alpha 2-macroglobulin. It did not inactivate alpha 2-macroglobulin. Basilase did not have any of the following activities: thrombin-like, factor X-like, protein C activating, or urokinase-like. It caused neither hemorrhage nor platelet aggregation. In spite of its proteolytic activity, basilase did not hydrolyze the membranes of platelets. Basilase had 24% alpha-helix, 31% beta-sheet, 25% turns, and 20% unordered structure, as determined by Fourier Transform Infrared spectroscopy. Basilase is an enzyme that hydrolyzes fibrin directly without activation of plasminogen.
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PMID:Biochemical characterization of basilase, a fibrinolytic enzyme from Crotalus basiliscus basiliscus. 789 51

The observation that urokinase infusion increases circulating levels of the anticoagulant activated protein C (APC) in baboons implies that APC might be elevated during thrombolytic therapy. Patients undergoing coronary thrombolysis showed an 11-fold increase (means from 6 to 69 micrograms/L) in APC during infusion of streptokinase. Thrombolytic therapy thus generates at least two potent antithrombotic factors in the circulation--the fibrinolytic enzyme, plasmin, and the anticoagulant enzyme, APC. APC may help prevent reocclusion during or after thrombolysis.
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PMID:Generation of activated protein C during thrombolysis. 790 87


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