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 separate experiments, antibodies to plasminogen, factor X and protein C were applied to microtitre trays as commonly used in enzyme-linked immunoassays. After incubation with dilute normal human plasma as a source of the corresponding proenzyme antigen, the wells were exposed to dilutions of various snake venoms. After thorough washing, the microtitre tray wells were tested overnight with chromogenic tripeptide substrates known to be relatively specific for the activated forms of the above factors, i.e., plasmin, factor Xa and activated protein C. The immunochromometric assay described detected two new activators of protein C in Agkistrodon piscivorus and Agkistrodon contortrix venoms and a new factor X activator in Agkistrodon rhodostoma venom. Gel filtration of the latter venom indicated that the factor X activator eluted with high molecular weight, was clearly distinct from the peak fibrinogen clotting activity (Ancrod) and appeared to have no procoagulant activity. Although several Bothrops venoms appeared to contain plasminogen activator by this technique, the observed strong chromogenic activity was observed in microtitre wells independently of plasminogen and represented nonspecific amidase activity.
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PMID:Detection of specific proenzyme activators in snake venoms by a new immunoabsorbant-chromogenic substrate method. 384 Oct 12

Mononuclear leukocytes release an inhibitor of plasminogen activators. Mononuclear leukocyte mixtures (400 to 1,000/mm3) lysed fibrin (8.3 microM) clots in the presence of plasminogen (0.58 microM). Anti-urokinase IgG (0.16 microM) inhibited this fibrinolysis. 2-Deoxyglucose (5 mM) and oligomycin (2.3 microM) also inhibited fibrinolysis. Incubation of mononuclear leukocytes (3,200/microliter) with phorbol-12 myristate 13-acetate (20 nM) for ten minutes at 37 degrees C aggregated the monocyte and platelet components and inhibited fibrinolysis. The releasate from these stimulated cells in dilutions ranging from undiluted to 1:16 inhibited urokinase (1.6 pM) and tissue plasminogen activator (1.4 pM). This releasate did not inhibit plasmin (2.5 nM). Incubation of this releasate with activated protein C (33 nM to 333 nM) for ten minutes at 37 degrees C before addition of either urokinase, or tissue plasminogen activator and plasminogen completely prevented this inhibition. Thrombin, factor Xa, DIP-activated protein C had no affect on this inhibition. We conclude that activated protein C facilitates fibrinolysis by preventing inhibition of plasminogen activators. This may be a mechanism by which activated protein C increases fibrinolytic activity in vivo.
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PMID:A new function for activated protein C: activated protein C prevents inhibition of plasminogen activators by releasate from mononuclear leukocytes--platelet suspensions stimulated by phorbol diester. 392 Jul 76

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

A DEAE-Sephadex column chromatography step utilized to purify human Factor VII consistently yields a protein peak between the factor VII activity peak and prothrombin, factor X and factor IX activity peak (S.P. Bajaj, S.I. Rapaport, and S.F. Brown: J. Biol. Chem. 251, 253-259, 1981). We now report that this protein peak contains protein C and protein S. Preparative disc polyacrylamide gel electrophoresis of the proteins in this peak permitted a complete separation of protein C from protein S. Protein C at this step usually contained approximately 5-10% of Factor X, which could be removed by a goat anti-human Factor X antibody column. For a typical preparation, starting with 10L of plasma, the yield of Protein C was 5 mg and of protein S was 4 mg. Both proteins revealed apparent homogeneity in sodium dodecyl sulfate gel electrophoretic system. beta-Protein C and beta-protein S were not observed in our preparations starting with plasma collected directly into citrate anticoagulant containing benzamidine and soybean trypsin inhibitor, suggesting that these beta forms of protein C and protein S, isolated by other investigators, are slightly degraded forms of the native proteins. Antisera generated to these proteins were monospecific and could be used to monitor column fractions during purification. When examined by immunoelectrophoresis, the electrophoretic mobility of protein S in plasma was slower than that of isolated protein S. When exposed to plasmin, protein C was activated slightly and then rapidly degraded.
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PMID:A procedure for isolation of human protein C and protein S as by-products of the purification of factors VII, IX, X and prothrombin. 622 44

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

Antihemophilic factor concentrates were surveyed for amidolytic activity on the chromogenic substrates S2238, S2302, S2222, and S2251, which are sensitive to thrombin, kallikrein, factor Xa, and plasmin, respectively. For antihemophilic factor concentrates from two manufacturers, the rates of amidolysis of S2238 and S2302 were approximately an order of magnitude greater than the rates of amidolysis of S2222 and S2251. The S2238 and S2302 activities were characterized by quantitating their interactions with specific substrates or inhibitors. The Km for amidolysis of S2238 was 558 mumol/L, which is 80 times higher than for thrombin but in close agreement to the reported value for activated protein C. The S2238 activity was not inhibited by the thrombin-specific inhibitor dansylarginine N-(3-ethyl-1,5-pentanediyl)amide, nor by soybean trypsin inhibitor or micromolar concentrations of antithrombin III in the presence of heparin. The S2238 activity was inhibited by D-Phe-Pro-Arg-CH2Cl, but with an estimated second-order rate constant of 3 X 10(5) mol/L-1 minute-1, approximately 1000 times less than for thrombin. These data are consistent with the identity of the S2238 activity as activated protein C. On the other hand, the S2302 activity in antihemophilic factor concentrates was most likely attributable to kallikrein. This was based on the agreement with authentic kallikrein of the Km for S2302 of 154 mumol/L as well as by the rapid inactivation by nanomolar concentrations of the kallikrein-specific inhibitor D-Phe-Phe-Arg-CH2Cl. However, the relative resistance of the S2302 activity to inhibition by soybean trypsin inhibitor or antithrombin III and the partial inhibition by aprotinin suggested that a large proportion of the kallikrein was bound to alpha 2-macroglobulin. This was confirmed by immunoprecipitation using specific anti alpha 2-macroglobulin IgG. The potential for proteolysis of factor VIII:von Willebrand protein during its purification from antihemophilic factor concentrates was demonstrated, and the proteolyzed factor VIII coagulant species was characterized. High-pressure gel permeation chromatography of purified factor VIII:von Willebrand protein at high ionic strength resulted in two sharp peaks of factor VIII procoagulant activity. The earlier eluting peak corresponded with the void volume, and the later peak eluted with an apparent molecular weight of 53,000 daltons. Immediately after separation, the 53,000-dalton factor VIII coagulant had at least a 100-fold higher specific activity than the factor VIII coagulant present in the void volume. However, the 53,000-dalton factor VIII coagulant was labile, with a half-life of 80 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Characterization of proteases in AHF concentrates: effect on factor VIII:von Willebrand protein as assessed by high-pressure gel permeation chromatography. 643 16

Tissue kallikrein and factor Xa were found to activate tissue plasminogen activator (t-PA) at a rate comparable with that of plasmin. During the activation reaction, the single-chain molecule was converted into a two-chain form. A slight t-PA activating activity was also found in plasma kallikrein. Other activated coagulation factors, factor XIIa, factor XIa, factor IXa, factor VIIa, thrombin and activated protein C had no effect on t-PA activation. t-PA was also activated by a tissue kallikrein-like enzyme that was isolated from the culture medium of melanoma cells. These results indicate that tissue kallikrein and factor Xa may participate in the extrinsic pathway of human fibrinolysis.
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PMID:Proteolytic activation of tissue plasminogen activator by plasma and tissue enzymes. 656 16

More than 100 chromogenic and fluorogenic peptide substrates are now available for the evaluation of coagulation and related parameters. Many of these substrates exhibit undesirable physical properties, such as insolubility, surface adsorption, and interaction with endogenous plasma proteins. Some of these substrates are capable of inhibiting serine protease generation during activation in the global assay. In order to develop synthetic chromogenic substrates with desirable physical and biochemical characteristics, modified amino acids, such as CHG, CHT, and Nleu, have been utilized. Similarly, to provide a favorable molecular environment to facilitate enzyme and synthetic substrate interactions, various molecular manipulations, such as the introduction of bulky groups, is helpful in developing substrates for protein Ca and C1-esterase. Substrates for Factor Xa, CH3-O-CO-CHG-Arg-pNA (bovine Xa, Km 2.5 X 10(-4) M; human, Km 3.5 X 10(-4) M); thrombin, H-D-CHT-Ala-Arg-pNA (bovine thrombin, Km 3 X 10(-6) M; human thrombin, Km 6 X 10(-6) M); plasmin, H-D-Nleu-CHT-Lys-pNA (human plasmin, Km 2.2 X 10(-5) M) were found to have identical or superior biochemical characteristics to the earlier substrates. These newer substrates were found to be more soluble (greater than 5 X 10(-4) M) in physiologic buffer, less susceptible to autoamidolysis at reaction conditions, and did not produce opacity of the test solution in final concentrations of 5 X 10(-4) M. Comparable results on normal and pathologic plasma samples were obtained in various laboratory assays that utilize currently available substrates for Factors Xa and IIa, kallikrein, and plasmin (R = greater than 0.9). We propose that prior to the application of a new synthetic substrate in a given assay, a careful biochemical and physical screening of the substrate, the assay conditions, and the interaction of substrates with plasma proteins is highly desirable.
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PMID:Newer synthetic peptide substrates in coagulation testing: some practical considerations for automated methods. 665 59

Recent progress in the measurements of the hemostatic markers enables us to assess the detailed profiles of hemostatic activation in various diseases. To evaluate the degree of hemostatic system activation in patients with cerebral thrombosis, detailed coagulation studies were performed in 28 patients with acute-phase cerebral thrombosis and in 36 with chronic-phase cerebral thrombosis, together with 6 with chronic-phase cerebral hemorrhage and 37 age-matched healthy volunteers. In both acute-phase and chronic-phase cerebral thrombosis, plasma levels of thrombin-antithrombin III complex, plasmin-alpha 2-plasmin inhibitor complex and D-dimer were significantly higher, and antithrombin III and protein C were significantly lower than those in the normal group. Plasma fibrinogen concentration was significantly higher in chronic-phase cerebral thrombosis than that in chronic-phase cerebral hemorrhage. No significant difference was found in these variables between acute-phase and chronic-phase cerebral thrombosis. In addition, there was no difference in these parameters between chronic phase cerebral hemorrhage and normal subjects. These findings indicate that a sustained activation of coagulation and fibrinolysis is present in cerebral thrombosis, and it might contribute to the pathogenesis of cerebral thrombosis.
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PMID:Sustained activation of blood coagulation in patients with cerebral thrombosis. 748 75


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