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)

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

The major plasmin inhibitors namely alpha2-plasmin inhibitor and alpha2-macroglobulin were compared for their effects on lysis of fibrin clot. Plasmin fibrinolytic activity was immediately inhibited by alpha2-plasmin inhibitor, whereas alpha2-macroglobulin inhibited plasmin progressively. Urokinase(plasminogen activator)-induced clot lysis was inhibited efficiently by alpha2-plasmin inhibitor present in the clot. Inhibition of urokinase-induced clot lysis by alpha2-macroglobulin was weak and the molar concentration necessary for alpha2-macroglobulin to achieve the same degree of inhibition as that achieved with alpha2-plasmin inhibitor was about 10 times higher than that of alpha2-plasmin inhibitor. Binding of Lys-plasminogen to fibrin was inhibited by alpha2-plasmin inhibitor but not by alpha2-macroglobulin. Molar concentrations of alpha2-plasmin inhibitor which were effective in inhibiting the binding were 30 times less than that of 6-aminohexanoicacid. alpha2-Plasmin inhibitor was found to interact with Lys-plasminogen to form a weakly-bound complex which is dissociable in the presence of 6-aminohexanoic acid, suggesting that inhibition of binding of Lys-plasminogen to fibrin by alpha2-plasmin inhibitor may be due to interaction of alpha2-plasmin inhibitor with a specific site of the plasminogen molecule and that the site may be 6-aminohexanoic acid-binding site. It is suggested that alpha2-plasmin inhibitor is more reactive and efficient inhibitor of fibrinolysis than alpha 2-macroglobulin.
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PMID:Effects of alpha2-plasmin inhibitor on fibrin clot lysis. Its comparison with alpha2-macroglobulin. 7 50

Three types of plasminogen activator could be distinguished in extracts from human uterine tissue. The activators differed in thermostability or in mode of inhibition by EACA. All the extracts contained stable as well as labile activators. The saline extracts were uniformly inhibited by increasing concentrations of EACA. Extracts made with 2 M ammonium thiocyanate were either uniformly inhibited by EACA or showed deflections indicating contamination with an activator, which was inhibited in a biphasic manner. It was possible to distinguish between: (1) An activator, abundantly present in the tissue, which was uniformly inhibited and stable. (2) Another uniformly inhibited activator, which was labile. (3) An activator, inhibited in a biphasic manner, similar to urokinase, which was present in varying amounts in uteri with the endometrium in the proliferative phase. Gel filtration of the uterine extracts showed two major activity peaks corresponding to particle sizes of 60,000 dalton and about 10,000 dalton. Antiserum to purified plasminogen activator, prepared from porcine ovaries, inhibited the activity of the human uterine extracts, but not the activities of human urokinase or urine. Urokinase antiserum in a concentration completely inhibiting human urine or urokinase, inhibited only 10% or less of the activities of human uterine extracts.
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PMID:Separation of plasminogen activators from human uterine tissue and a comparison with activators from human urine and porcine tissue. 11 1

A method is described by which the heavy chain of human plasmin, obtained by partial reduction of urokinase-activated plasminogen with 2-mercaptoethanol, is adsorbed on lysine coupled to polyacrylamide. The heavy chain is recovered from the adsorbent by elution with 6-aminohexanoic acid (yield 60-65%). Sulfhydryl titrations of the heavy chain showed that the partial reduction involved primarily the cleavage of the sole interchain disulfide bridge of plasmin. Dodecylsulfate-polyacrylamide electrophoresis gave essentially a single band corresponding to a component of about 60000 molecular weight. The NH2-terminal amino acid was predominantly threonine. 6-Aminohexanoic acid at different concentrations caused significant variations of the sedimentation and diffusion constants of the heavy chain indicating inhibitor-induced conformational alterations of the protein. The present results suggest that in plasmin only the heavy chain is capable of interacting with 6-aminohexanoic acid, and it appears that it is primarily this chain which plays an important role in the inhibition of the enzyme by 6-aminohexanoic acid.
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PMID:A new method of isolation and some properties of the heavy chain of human plasmin. 12 54

Plasminogen and plasminogen derivatives which contain lysine-binding sites were found to decrease the reaction rate between plasmin and alpha2-antiplasmin by competing with plasmin for the complementary site(s) in alpha2-antiplasmin. The dissocwation constant Kd for the interaction between intact plasminogen (Glu-plasminogen) and alpha2-antiplasmin is 4.0 microM but those for Lys-plasminogen or TLCK-plasmin are about 10-fold lower indicating a stronger interaction. The lysine-binding site(s) which is situated in triple-loops 1--3 in the plasmin A-chain is mainly responsible for the interaction with alpha2-antiplasmin. The interaction between Glu-plasminogen and alpha2-antiplasmin furthermore enhances the activation of Glu-plasminogen by urokinase to a comparable extent as 6-aminohexanoic acid, suggesting that similar conformational changes occur in the proenzyme after complex formation. Fibrinogen, fibrinogen digested with plasmin, purified fragment E and purified fragment D interfere with the reaction between plasmin and alpha2-antiplasmin by competing with alpha2-antiplasmin for the lysine-binding site(s) in the plasmin A-chain. The Kd obtained for these interactions varied between 0.2 microM and 1.4 microM; fragment E being the most effective. Thus the fibrinogen molecule contains several complementary sites to the lysine-binding sites located both in its NH2-terminal and COOH-terminal regions; these sites are to a large extent.
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PMID:On the specific interaction between the lysine-binding sites in plasmin and complementary sites in alpha2-antiplasmin and in fibrinogen. 15 66

Normal human plasma contains acid-stable as well as labile plasminogen activators. The activity of activators in plasma euglobulins was inhibited by EACA in an uniform pattern, similar to that obtained with the major activators in human uterine tissue or with the purified porcine tissue activator, but different from the patterns obtained with plasmin or with urokinase. Gel filtration at high ionic strength separated activators corresponding to particle sizes of 60,000 dalton and about 10,000 dalton, corresponding to two activators similarly obtained from human tissue. The 60,000 dalton activator was precipitated in the euglobulin fraction. Its concentration increased in plasma after exercise. The 10,000 dalton activator was found mainly in the supernatant. Gel filtration in 0.15 M solutions yielded activators in fractions of molecular sizes of 100-140,000 dalton and 200,000 dalton or larger. The activity of normal and exercise euglobulins was inhibited by antiserum to a plasminogen activator prepared from porcine tissue, but it was not inhibited by antiserum to urokinase. Plasminogen activators in human plasma euglobulins resembled immunochemically the activators in human uterine tissue.
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PMID:Separation of plasminogen activators from human plasma and a comparison with activators from human uterine tissue and urine. 48 46

The binding, internalization, and degradation of tissue-type plasminogen activator (t-PA) were studied in a rat hepatoma (Novikoff) cell line. Binding of t-PA to specific saturable high affinity binding sites (Kd = 12 nM, 54,000 sites/cell) was followed by internalization and degradation and did not require a functional active site. The catabolism of t-PA was not inhibited by an excess of urokinase-type plasminogen activator (u-PA), and t-PA bound to Novikoff membranes was not complexed to PAI-1, suggesting a mechanism independent of PAI-1. Additionally, a mannose receptor is not involved since t-PA binding was not influenced by an excess of mannose, galactose, ovalbumin, or EDTA. Furthermore, the degradation of t-PA was not influenced by 10 mM 6-aminohexanoic acid, a lysine analogue. The t-PA receptor binds to and can be eluted from wheat germ agglutinin-Sepharose. Cross-linking of t-PA with partially purified receptor and ligand blot analysis, suggest that t-PA binds to two proteins, a principal one of 55 kDa and a minor one of 43 kDa. Novikoff cells are able also to bind (Kd = 1.4 nM, 25,000 sites/cell) and degrade u-PA. The binding was inhibited by pro-u-PA and the amino-terminal fragment of u-PA, but not by an excess of t-PA. The u-PA receptor, but not the t-PA receptor, was removed by treatment with phosphatidylinositol-specific phospholipase C. Our results show that the clearance receptor for t-PA on Novikoff cells is different from the mannose receptor and the PAI-1-dependent receptor described in other cells. The rat hepatoma cells are thus a good model to study the PAI-1 independent hepatocyte-specific clearance of t-PA.
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PMID:Demonstration of a specific clearance receptor for tissue-type plasminogen activator on rat Novikoff hepatoma cells. 131 32

The amidolytic activity of plasmin with the chromogenic substrate H-D-valyl-L-leucyl-L-lysine p-nitroanilide (S-2251) is stimulated by oleic acid in a dose-dependent and saturable fashion. The activity of plasmin on S-2251 in the presence of oleic acid followed a sigmoidal kinetic pattern, with an almost 4-fold stimulation of activity at 60 microM-oleic acid. Half-maximal stimulation occurred at an oleic acid level of 19.5 microM. The amino acid analogue 6-aminohexanoic acid (AHA), which is known to bind to lysine-binding sites in plasmin, suppressed the stimulatory effect of oleic acid in a concentration-dependent manner; at 0.3 mM-AHA, about 70% of the oleic acid-dependent enhancement of plasmin activity was abolished. The l/v versus 1/[S] plot for plasmin changed in the presence of oleic acid from a linear to a non-linear curve, suggesting positive co-operativity. 14C-labelled oleic acid bound to plasmin, and the bound ligand was displaced by an excess of unlabelled oleic acid. Oleic acid also produced a marked (40-fold) stimulation of the plasminogen-dependent cleavage of S-2251 by urokinase. A half-maximal effect on plasminogen activation was obtained at 40 microM-oleic acid. The present findings suggest that the ability of oleic acid to stimulate plasmin activity and to enhance the conversion of plasminogen to plasmin depends on the interaction of oleic acid with specific lysine-binding sites in plasmin.
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PMID:Stimulation of plasmin activity by oleic acid. 153 91

The pathogenesis of Hailey-Hailey disease and Darier's disease was investigated using immunocytological and explant-tissue-culture techniques. There was breakdown of the intercellular adhesions between keratinocytes in explants from clinically uninvolved skin of patients with Hailey-Hailey disease or Darier's disease. The major desmosomal components were present in the cultures and were expressed in a punctate peripheral pattern at cell-cell contact sites, but there was diffuse staining of acantholytic cells. Plasminogen, which is expressed by basal keratinocytes in normal skin, was detected in association with suprabasal acantholytic cells in skin biopsies from these diseases. Plasminogen was reversibly displaced from the cells by 6-aminohexanoic acid, suggesting that binding is mediated by a reaction with the lysine receptor on the plasminogen molecule. Plasminogen was also detected in separating cells in explant cultures and there was cytoplasmic expression of the plasminogen activator urokinase by these cells. These abnormalities are not unique to either disease and do not account for the phenotypic differences between Darier's disease and Hailey-Hailey disease, but plasmin generation may have a role in perpetuating cell separation.
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PMID:Cell adhesion in Hailey-Hailey disease and Darier's disease: immunocytological and explant-tissue-culture studies. 175 48

This study demonstrates an enhancing effect of aspirin on the amidolytic activity of plasmin. The stimulation of plasmin by aspirin was concentration-dependent and was attained at aspirin concentrations above 2 x 10(-4) M. Aspirin produced a small, reproducible and statistically significant stimulation of the chromogenic activity of plasmin upon H-D-Valyl-L-Leucyl-L-Lysine-p-nitroanilide (S-2251) or pyro-Glu-Gly-Arg-p-nitroanilide (S-2444). Kinetic analysis demonstrated a slight decrease in the affinity of plasmin for substrate S-2251 in the presence of aspirin, reflected by a change of the Km from 3.2 x 10(-4) M to 3.8 x 10(-4) M, and an increase of the Vm. The reciprocal Lineweaver-Burk curve indicated an uncompetitive type of stimulation. The stimulatory effect of aspirin was abolished by the lysine analogue 6-aminohexanoic acid (AHA) but not by the alpha-amino acid glutamic acid. The effect of AHA suggests a specific involvement of lysine binding sites (LBS) on plasmin in the interaction of the enzyme with aspirin. Transient acidification of plasmin abolished its response to aspirin, to AHA and to their combination. The addition of aspirin to diluted human control or pregnancy plasma in vitro stimulated the plasma-mediated cleavage of the chromogenic substrate S-2251. In contrast to its effect on plasmin, aspirin failed to change the activity of tissue-type or urokinase-type plasminogen activators. It is conceivable that in addition to the antithrombotic effect of aspirin ascribed to its interaction with the platelets, aspirin also directly stimulates plasmin activity.
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PMID:Stimulation of plasmin activity by aspirin. 182 77


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