Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzyme-linked immunosorbent assay (ELISA) has been developed for the quantification of alpha 1-antitrypsin-human leukocyte elastase (alpha 1AT-E) complexes. In the ELISA, the alpha 1AT-E complex is bound to a surface by rabbit antileukocyte elastase antibody, and the inhibitor-proteinase complex is quantified by a second antibody, rabbit anti-alpha 1-antitrypsin F(ab')2, labeled with alkaline phosphatase. alpha 1AT-E complexes were detected when a final concentration of 2.2 nmol/liter of leukocyte elastase was added to plasma. The concentration of these complexes increased with additional elastase. In clotting blood, alpha 1AT-E complexes were generated in parallel with the conversion of 125I-fibrinogen to fibrin, whereas alpha 2-plasmin inhibitor-plasmin (alpha 2PI-P) complexes were not formed. The concentration of alpha 1AT-E complexes in 19 of 21 controls was less than 2.2 nmol/liter. Patients with laboratory evidence for disseminated intravascular coagulation (DIC) demonstrated elevated alpha 2PI-P complexes with either increased or normal concentrations of alpha 1AT-E complexes. Patients without evidence for DIC, but who demonstrated prolonged reptilase clotting times, were studied. This group had increased alpha 1AT-E but normal alpha 2PI-P complex levels, raising the possibility that elastase release in vivo may be accompanied by limited degradation of fibrinogen. These assays thus serve as useful probes for the study of leukocyte activation and of the interactions between cellular and plasma proteolytic enzyme systems.
 ...
PMID:Alpha-1-antitrypsin-human leukocyte elastase complexes in blood: quantification by an enzyme-linked differential antibody immunosorbent assay and comparison with alpha-2-plasmin inhibitor-plasmin complexes. 621 25

Plasminogen, a precursor of proteolytic enzyme plasmin which lyses thrombi in vivo, is postulated to be adsorbed onto fibrin and is converted into a modified form by plasmin. The properties of the modified form examined in vitro support this hypothesis. Nevertheless, it has been postulated that no conversion of native plasminogen into the modified form occurs in plasma, since alpha 2-plasmin inhibitor rapidly inactivates plasmin formed. However, we suggested production of the modified form in the "post-exercise" plasma. The present study was undertaken to examine production of the modified form in a simpler system, urokinase-activated plasma. The amount of the modified form in the plasma was estimated using the previous method with modification, epsilon-aminocaproic acid-containing polyacrylamide gel disc electrophoresis. The amount in the post-exercise plasma was also re-estimated by the present method. The amount of the modified form increased with the increase in urokinase concentration added to plasma. The presence of the modified form in the post-exercise plasma was also confirmed. The modified form could be produced in the plasma where an excess amount of alpha 2-plasmin inhibitor was expected to exist. The present results indicate that conversion of native plasminogen into the modified form may occur in vivo, supporting the hypothesis mentioned above.
 ...
PMID:Production of the modified form of human plasminogen in the plasma activated by urokinase. 622 15

In spontaneous fibrinolysis of an alpha 2-plasmin inhibitor-deficient plasma clot or tissue-type plasminogen activator-induced fibrinolysis in a purified system without alpha 2-plasmin inhibitor, the lysis was faster when factor XIII-mediated crosslinking of fibrin to fibrin did not occur. During the initial period, the binding of plasminogen to fibrin steadily increased with incubation time. The initial level and subsequent increase of the binding, which may be critical for the subsequent development of fibrinolysis, were more remarkable when fibrin was not crosslinked. The amount of glu- or lys-plasminogen bound to noncrosslinked fibrin was around 4 or 1.5 times larger than the amount of the respective plasminogen bound to crosslinked fibrin. Plasmin was also found to be bound to noncrosslinked fibrin twice as much as the amount bound to crosslinked fibrin. Structural changes induced by crosslinking of fibrin alpha-chain may reduce either the affinity or the number of available complementary sites to lysine binding sites of plasmin(ogen), thereby decreasing the binding of plasmin(ogen) to fibrin. These results suggest that an increased affinity of noncrosslinked fibrin for plasmin(ogen) is contributory to the accelerated fibrinolysis observed in factor XIII deficiency, in addition to an absence of crosslinking of alpha 2-plasmin inhibitor to fibrin.
 ...
PMID:Differential binding of plasminogen to crosslinked and noncrosslinked fibrins: its significance in hemostatic defect in factor XIII deficiency. 623 70

Vascular or tissue-type plasminogen activator (TPA) is a key enzyme in physiologic fibrinolysis. To study the role of prostaglandins in modulating the synthesis and release of TPA in vivo, we prospectively studied the effect of aspirin (650 mg/d X 2) on TPA activity in 13 human subjects before and after 10 min of forearm venous occlusion. TPA activity was quantified by a newly developed enzyme-linked immunosorbent assay that both measures and differentiates between TPA and urokinase (UK)-like plasminogen activator activity. This assay is based on the observation that the concentration of alpha 2-plasmin inhibitor-plasmin complexes in Reptilase-clotted plasma increases linearly in proportion to the amount of activator added. Resting TPA activity was higher in women than in men (0.56 +/- 0.59 vs. 0.15 +/- 0.11 U/ml, P = 0.049). Venous occlusion induced an eightfold rise in TPA activity in women (to 4.5 U/ml, P = 0.006) and a 15-fold rise in men (to 2.28 U/ml, P = 0.004), whereas UK activity was not detected. Aspirin inhibited the rise in TPA activity after venous occlusion by 69% in men (P = 0.004) and 70% in women (P = 0.014). In contrast, aspirin had no effect on pre- or post-occlusion hematocrits or Factor VIII-related antigen levels. There was no correlation between plasma salicylate level and percentage inhibition of TPA. Neither exogenous aspirin (0-1 microgram/ml) nor salicylate (0-70 micrograms/ml) inhibited the generation of alpha 2-plasmin inhibitor-plasmin complexes by exogenous TPA or interfered with the assay system. We conclude that aspirin may have an antifibrinolytic effect in man that has not been previously described.
 ...
PMID:Aspirin inhibits vascular plasminogen activator activity in vivo. Studies utilizing a new assay to quantify plasminogen activator activity. 623 45

Fibrinolytic inhibitor was prepared from human aortas and some of its biochemical properties were investigated. The fibrinolytic inhibitor suppressed urokinase activity, but did not inhibit plasmin activity when assayed by fibrin plate method and synthetic fluorogenic substrate method. The urokinase inhibitor was a glycoprotein and migrated similar to alpha-globulin upon fibrin-agar electrophoresis. The molecular weight determined by gel filtration was approximately 98,000. The urokinase inhibitor was immunologically different from other known plasma protease inhibitors, such as alpha 2-plasmin inhibitor, alpha 2-macroglobulin, and alpha 2-antitrypsin. The interaction of urokinase with the inhibitor was dose-dependent. Progressive inactivation of urokinase occurred by increasing time of incubation with the inhibitor at 37 degrees C, and over 90% inhibition of urokinase required 30 min of incubation. The inhibitor of plasminogen activator in human aorta may be noteworthy in relation to thrombogenesis and atherogenesis.
 ...
PMID:Inhibitor of plasminogen activator in human arterial wall. II. Biochemical characterization. 623 47

The function of fibrinolysis is to dissolve fibrin clots. The agent of fibrinolysis is plasmin, a glycoprotein with gram molecular weight (GMW) of 90,000. Under natural conditions, plasminogen is converted to plasmin by tissue plasminogen activator (TPA). Activation occurs on the fibrin surface, thus confining proteolytic activity to the appropriate site. Tissue plasminogen activator, produced by monoclonal methods, has recently been made available for limited therapeutic use. Currently streptokinase and urokinase are widely used therapeutically to activate plasminogen. These agents cause plasmin to be formed which is free in the circulation as well as bound to fibrin, resulting in proteolysis of circulating plasminogen and clotting factors. Fibrinolytic therapy has proven to be more beneficial than anticoagulation alone for deep vein thrombi and for pulmonary emboli. During therapy, laboratory studies demonstrate reduced concentrations of plasminogen, fibrinogen, and of alpha-2 plasmin inhibitor, and prolongation of activated partial thromboplastin time and thrombin time. Laboratory findings must be correlated with the clinical course. Demonstration of circulating plasmin-antiplasmin complex may be a useful indicator of active fibrinolysis.
 ...
PMID:Fibrinolysis--a review. 623 87

The site of synthesis of alpha 2-plasmin inhibitor (alpha 2-PI), a physiologic inhibitor of plasmin, is not known with certainty. We have studied the production and secretion of alpha 2-PI by three established human liver cell lines derived from hepatocellular carcinoma and hepatoblastoma (Hep G2, Hep 3B, and PLC/PRF/5). As measured by a specific radioimmunoassay, the titer of alpha 2-PI increased in the medium of Hep G2 and Hep 3B cells with time, but no significant amount of alpha 2-PI was found in the medium of PLC/PRF/5. There was no evidence for a significant intracellular pool of this protein. On immunodiffusion against anti-alpha 2-PI serum, alpha 2-PI secreted by Hep G2 (G2 alpha 2-PI) formed a simple precipitin line of complete identity with the alpha 2-PI present in plasma (plasma alpha 2-PI). G2 alpha 2-PI behaved similarly to plasma alpha 2-PI in Sephadex G-150 gel filtration, sucrose density-gradient centrifugation, and crossed immunoelectrophoresis. G2 alpha 2-PI inhibited plasmin activity instantaneously in a functional assay and formed a complex with plasmin demonstrable by crossed immunoelectrophoresis. De novo synthesis of alpha 2-PI was shown by the presence of specific immunoprecipitable radioactivity in the medium after 5 hr of labeling of the cells with [35S]methionine. Analysis of the immunoprecipitates by NaDodSO4/polyacrylamide gel electrophoresis showed a single peak of radioactivity corresponding to Mr 68,000. These results indicate that the liver is a site of alpha 2-PI production.
 ...
PMID:Synthesis and secretion of alpha 2-plasmin inhibitor by established human liver cell lines. 629 Oct 58

An acid-stable protease inhibitor (AS-PI) has been previously demonstrated in ascitic fluid from patients with ovarian carcinoma. In this study, the AS-PI was further purified using DEAE-cellulose and isoelectric focusing (IEF), and a partial characterization was undertaken. On DEAE-cellulose ion-exchange column chromatography, AS-PI activity was observed in both adsorbed and non-adsorbed fractions. The former represented the main AS-PI peak. By IEF, the respective pI values were 1.6 and 4.5. By gel filtration, the molecular weight of the main (adsorbed fraction) AS-PI was 78 000. This AS-PI strongly inhibited trypsin and to a lesser extent chymotrypsin, but exerted no inhibitory effect on plasmin. It slightly inhibited SH proteases such as papain and ficin. Immunologically, AS-PI was distinct from alpha 1-antitrypsin, alpha 1-antichymotrypsin, inter-alpha-trypsin inhibitor, antithrombin III, C1-inactivator, alpha 2-macroglobulin and alpha 2-plasmin inhibitor. The main AS-PI reacted with and was neutralized by antiurinary trypsin inhibitor serum, and on immunoelectrophoresis, had a mobility slightly cathodal to serum albumin.
 ...
PMID:Further purification and characterization of acid-stable protease inhibitor from ascites of an ovarian carcinoma patient. 643 8

alpha 2-Plasmin inhibitor was purified from rat plasma by the procedures including sequential lysine-Sepharose chromatography, ammonium sulfate precipitation and plasminogen-Sepharose, DEAE-Sephadex, concanavalin A-Sepharose, and Sephadex G-200 chromatographies. The final preparation was homogeneous as judged by sodium dodecyl sulfate polyacrylamide gel- and immuno-electrophoresis. It was a single polypeptide chain with a molecular weight of about 7.1 X 10(4) daltons and was found to possess fast-acting antiplasmin activity. There existed other molecular forms of alpha 2-plasmin inhibitor-related antigen with molecular weight of 6.3 X 10(4) and 6.1 X 10(4) daltons. The latter was found to be inactive in binding to plasminogen and in inhibiting plasmin activity. Normal plasma level of alpha 2-plasmin inhibitor in rats was immunologically determined to be 7.9 +/- 0.8 mg/dl. Indirect evidence was obtained that rat alpha 2-plasmin inhibitor was incorporated into cross-linked fibrin during blood clotting.
 ...
PMID:Purification and some properties of rat alpha 2-plasmin inhibitor. 643 28

The concentration of alpha 2-plasmin inhibitor in blood plasma is higher than that in serum obtained from the blood clotted in the presence of calcium ions, but is the same as that in serum obtained in the absence of calcium ions. Radiolabeled alpha2-plasmin inhibitor was covalently bound to fibrin only when calcium ions were present at the time of clotting of plasma or fibrinogen. Whereas, when batroxobin, a snake venom enzyme that lacks the ability to activate fibrin-stabilizing factor, was used for clotting fibrinogen, the binding was not observed. When fibrin-stablizing, factor-deficient plasma was clotted, the specific binding of alpha 2-plasmin inhibitor to fibrin did not occur even in the presence of calcium ions and the concentration of alpha 2-plasmin inhibitor in serum was the same as that in plasma. Monodansyl cadaverine, a fluorescent substrate of the fibrin-stablizing factor, was incorporated into alpha 2-plasmin inhibitor by activated fibrin-stablizing factor. All these findings indicate that alpha 2-plasmin inhibitor is cross-linked to fibrin by activated fibrin-stabilizing factor when blood is clotted. Analysis of alpha 2-plasmin inhibitor-incorporated fibrin by sodium dodecyl sulfate gel electrophoresis showed that the inhibitor was mainly cross-linked to polymerized alpha-chains of cross-linked fibrin. Cross-linking of alpha 2-plasmin inhibitor to fibrin renders fibrin clot less susceptible to fibrinolysis by plasmin.
 ...
PMID:Cross-linking of alpha 2-plasmin inhibitor to fibrin by fibrin-stabilizing factor. 644 5


<< Previous 1 2 3 4 5 6 7 8 9 10