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)

We investigated the effect of plasmin on the release of sulfated glycosaminoglycans (GAG) from cultured vascular smooth muscle cells. Confluent cultures of vascular smooth muscle cells from bovine aorta were labelled with [35S]sulfate and incubated at 37 degrees C for principally 60 min in a serum-free medium in the presence of plasmin. Plasmin at 10 mU/ml (approximately 2.7 micrograms/ml) and above significantly increased the release of [35S]sulfate-labeled GAG (35S-GAG) from the cell layer after a 60 min incubation. A time course study showed that plasmin at 10 mU/ml significantly increased the 35S-GAG release after 20 min and longer. However, plasminogen at 100 mU/ml and below did not cause a significant change of the 35S-GAG release after a 90 min incubation. A characterization of 35S-GAG revealed that plasmin increased both dermatan sulfate and the other 35S-GAG in the medium. Plasmin at 100 mU/ml enhanced the cell detachment significantly but only slightly. From these results, it was suggested that a endogenous thrombin inhibitor heparin cofactor II may be activated in the liquid phase by dermatan sulfate released from plasmin-stimulated vascular smooth muscle cells when the vascular is disrupted and plasma is exposed to extravessel.
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PMID:Plasmin stimulates the release of dermatan sulfate from vascular smooth muscle cells in culture. 138 67

Anabolic steroids are known to increase the plasma concentrations of certain plasma proteins. In four patients given treatment with danazol, an attenuated androgen, the concentrations of heparin cofactor II, Hageman factor (factor XII), protein C, and both free and total protein S increased significantly when tested 39 to 103 days after the start of therapy. The titers of these proteins in samples obtained 21 days to 5 years after therapy was discontinued were similar to those before treatment, except for total protein S, the titer of which remained elevated. No significant changes in the titers of C4b binding protein or plasma plasmin inhibitory activity were found.
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PMID:Some clotting factors in plasma during danazol therapy: free and total protein S, but not C4b-binding protein, are elevated by danazol therapy. 153 44

125I-labeled heparin cofactor II (HCII) was mixed with plasma and coagulation was initiated by addition of CaCl2, phospholipids, and kaolin or tissue factor. In the presence of 67 micrograms/ml of dermatan sulfate, radioactivity was detected in a band which corresponded to the thrombin-HCII complex (Mr = 96,000) upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. No other complexes were observed. The thrombin-HCII complex was undetectable when 5 units/ml of heparin was present or when prothrombin-deficient plasma was used. In experiments with purified proteases, HCII did not significantly inhibit coagulation factors VIIa, IXa, Xa, XIa, XIIa, kallikrein, activated protein C, plasmin, urokinase, tissue plasminogen activator, leukocyte elastase, the gamma-subunit of nerve growth factor, and the epidermal growth factor-binding protein. HCII inhibited leukocyte cathepsin G slowly, with a rate constant of 8 X 10(4) M-1 min-1 in the presence of dermatan sulfate. These results indicate that the protease specificity of HCII is more restricted than that of other plasma protease inhibitors and suggest that the anticoagulant effect of dermatan sulfate is due solely to inhibition of thrombin by HCII.
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PMID:The protease specificity of heparin cofactor II. Inhibition of thrombin generated during coagulation. 383 15

The present paper describes chemical and functional properties of protease nexin, a serine protease inhibitor released from cultured human fibroblasts. It is shown that protease nexin is actually synthesized by fibroblasts and represents about 1% of their secreted protein. Analysis of the amino acid composition of purified protease nexin indicates that it is evolutionarily related to antithrombin III and heparin cofactor II. Protease nexin contains approximately 6% carbohydrate, with 2.3% amino sugar, 1.1% neutral sugar, and 3.0% sialic acid. The Mr calculated from equilibrium sedimentation analysis is 43,000. Protease nexin is a broad specificity inhibitor of trypsin-like serine proteases. It reacts rapidly with trypsin (kassoc = 4.2 +/- 0.4 X 10(6) M-1 s-1), thrombin (kassoc = 6.0 +/- 1.3 X 10(5) M-1 s-1), urokinase (kassoc = 1.5 +/- 0.1 X 10(5) M-1 s-1), and plasmin (kassoc = 1.3 +/- 0.1 X 10(5) M-1 s-1), and slowly inhibits Factor Xa and the gamma subunit of nerve growth factor but does not inhibit chymotrypsin-like proteases or leukocyte elastase. In the presence of heparin, protease nexin inhibits thrombin at a nearly diffusion-controlled rate. Two heparin affinity classes of protease nexin can be detected. The present characterization pertains to the fraction of protease nexin having the higher affinity for heparin. The low affinity material, which is the minor fraction, is lost during purification.
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PMID:Protease nexin. Properties and a modified purification procedure. 399 57

We investigated the relationship between fasting insulin level and various hemostatic factors, including fibrinolytic factors (active plasminogen activator inhibitor-1 (PAI-1), tissue type plasminogen activator (tPA)-PAI-1 complex, plasmin-alpha 2-plasmin inhibitor (PIC), and D-dimer), coagulation factors (activated factor VII, factor VII coagulant activity and antigen, factor VIII, factor X, and fibrinogen), coagulation inhibitors (antithrombin III, heparin cofactor II, and protein C), and an acute phase marker (sialic acid) in 102 healthy individuals aged > or = 75 years (46 men and 56 women). Active PAI-1 levels had a significant negative correlation with PIC levels (r = -0.342, P = 0.0006), indicating that PAI-1 influences in vivo fibrinolytic activity in the very elderly. Gender differences were found in the relationship between insulin and hemostatic abnormalities, with the insulin level being positively correlated with coagulation factors in men (factor VIII activity: r = 0.422, P < 0.01; factor VII activity: r = 0.386, P < 0.01) and with hypofibrinolysis in women (active PAI-1: r = 0.549, P < 0.0001). Insulin levels were positively correlated with the levels of factor VII antigen and factor VII activity in men (P < 0.01), but there was no correlation with activated factor VII levels. The fasting insulin level was also correlated with the levels of heparin cofactor II and sialic acid in men (P < 0.05). However, other hemostatic factors were not related to the insulin level in either sex.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Gender differences of disturbed hemostasis related to fasting insulin level in healthy very elderly Japanese aged > or = 75 years. 757 76

Very-low-density lipoprotein receptor (VLDLR) and alpha2-macroglobulin receptor/low-density-lipoprotein-receptor-related protein (alpha2MR/LRP) are multifunctional endocytosis receptors of the low-density lipoprotein receptor family. Both have been shown to mediate endocytosis and degradation of complex between plasminogen activators and type-1 plasminogen-activator inhibitor (PAI-1) by cultured cells. We have now studied the specificity of binding and endocytosis by VLDLR and alpha2MR/LRP among a variety of serine proteinase/serpin complexes, including various combinations of the serine proteinases urokinase-type and tissue-type plasminogen activators, plasmin, thrombin, human leukocyte elastase, cathepsin G, and plasma kallikrein with the serpins PAI-1, horse leukocyte elastase inhibitor, protein C inhibitor, C1-inhibitor, alpha2-antiplasmin, alpha1-proteinase inhibitor, alpha1-antichymotrypsin, protease nexin-1, heparin cofactor II, and antithrombin III. Binding was estimated with radiolabelled ligands in ligand blotting analysis and microtiter well assays. Endocytosis was estimated by measuring receptor-associated protein (RAP)-sensitive degradation of radiolabelled complexes by Chinese hamster ovary cells transfected with VLDLR cDNA and by COS-1 cells, which have a high endogenous expression of alpha2MR/LRP. We found that the receptors bind with high affinity to some, but not all, combinations of plasminogen activators and thrombin with PAI-1, protease nexin-1, protein C inhibitor, and antithrombin III, while complexes of many serine proteinases with their primary inhibitor, i.e. plasmin/alpha2-antiplasmin complex, do not bind, or bind with a very low affinity. Both the serine proteinase and the serpin moieties contribute to the binding specificity. The binding specificities of VLDLR and alpha2MR/LRP are overlapping, but not identical. The results suggest that VLDLR and alpha2MR/LRP have different biological functions by having different binding specificities as well as by being expressed by different cell types.
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PMID:Specificity of serine proteinase/serpin complex binding to very-low-density lipoprotein receptor and alpha2-macroglobulin receptor/low-density-lipoprotein-receptor-related protein. 934 78

Accelerated thrombin generation is central to the development of hemostatic abnormalities during cardiopulmonary bypass (CPB) that are associated with both thromboembolic complications and serious, abnormal bleeding. Thrombin not only converts fibrinogen to fibrin, but also activates platelets and coagulation factors V, VIII, and XI and causes release of von Willebrand factor from vascular endothelium. Thrombin can also downregulate the hemostatic system by inducing formation of platelet inhibitory agents, such as nitric oxide and prostacyclin, and release of tissue plasminogen activator, facilitating activation of protein C, and releasing tissue factor pathway inhibitor. Excessive thrombin activity may also result in substantial consumption of platelets, fibrinogen, and labile coagulation factors and abnormal bleeding. Elevated tissue plasminogen activator levels secondary to activation of the contact system and surgery catalyze the formation of plasmin, which also consumes or internalizes platelet glycoprotein receptors and coagulation factors V, VIII, and fibrinogen. Heparin can reduce the generation of and mediate neutralization of excessive and CPB-associated thrombin activity. Heparin anticoagulation is commonly monitored with the activated clotting time (ACT). However, the ACT may be prolonged by factors other than heparin during CPB, such as hemodilution and hypothermia, and therefore may not accurately reflect the extent of anticoagulation by heparin. Aprotinin, a nonspecific serine protease inhibitor used with CPB, can also prolong celite-based ACT values, rendering it less reliable for monitoring heparin anticoagulation. Therefore, several alternative anticoagulation strategies have been recommended when aprotinin is used, such as a higher celite ACT trigger (>750 seconds), monitoring of whole blood heparin concentrations (eg, >2.7 U/mL), or administration of heparin based on a CPB duration-dependent, fixed-dose regimen. Administration of heparin doses higher than those generally recommended, as guided by predetermined, patient-specific whole blood heparin concentration measurements during bypass, can reduce excessive thrombin-mediated consumption of platelets and coagulation factors as well as post-CPB blood loss and blood component transfusions. New modalities of improving suppression of excess thrombin generation during CPB include use of heparin-bonded CPB circuits, heparin cofactor II or related analogs, supplemental antithrombin III, direct thrombin inhibitors (eg, hirudin, argatroban), and inhibitors of the contact and tissue factor pathways. The safety and efficacy of these approaches remains to be established by additional, appropriately powered, prospective studies.
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PMID:Anticoagulation and anticoagulation reversal with cardiac surgery involving cardiopulmonary bypass: an update. 1046 45

Serpins are the predominant protease inhibitors in the higher organisms and are responsible, in humans, for the control of many highly regulated processes including blood coagulation and fibrinolysis. The serpin inhibitory mechanism has recently been revealed by the solution of a crystallographic structure of the final serpin-protease complex. The serpin mechanism, in contrast to the classical lock-and-key mechanism, involves dramatic conformational change in both the inhibitor and the inhibited protein. The final result is a stable covalent complex in which the properties of each component are altered so as to allow clearance from the circulation. Several serpins are involved in hemostasis: antithrombin (AT) inhibits many coagulation proteases, most importantly factor Xa and thrombin; heparin cofactor II (HCII) inhibits thrombin; protein C inhibitor (PCI) inhibits activated protein C and thrombin bound to thrombomodulin; plasminogen activator inhibitor 1 inhibits tissue plasminogen activator; and alpha2-antiplasmin inhibits plasmin. Nearly all of these reactions are accelerated through interactions with glycosaminoglycans (GAGs) such as heparin or heparan sulfate. Recent structures of AT, HCII and PCI have revealed how in each case the serpin mechanism has been fine-tuned by evolution to bring about high levels of regulatory control, and how seemingly disparate mechanisms of GAG binding and activation can share critical elements. By considering the serpins involved in hemostasis together it is possible to develop a deeper understanding of their complex individual roles.
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PMID:Mechanisms of glycosaminoglycan activation of the serpins in hemostasis. 1287 Dec 89

The purpose of this study was to clarify the precise effect of argatroban on the inhibition of cytokine secretion induced by thrombin on synovial cells. The efficiency of thrombin inactivation by thrombin inhibitors was evaluated in human synovial fluids (SFs). In SFs from 13 osteoarthritis (OA) and 11 rheumatoid arthritis (RA) patients, thrombin, Factor Xa (FXa), plasmin activity, IL-6, MMP-3, VEGF, and D-dimer concentrations were measured. Tissue factor (TF) activity or IL-6, MMP-3, and VEGF secretion of human synovial cells with or without thrombin and argatroban were measured. The efficiency of thrombin inactivation in SFs was compared for thrombin inhibitors: argatroban, antithrombin III (ATIII), or heparin cofactor II (HCII). In SFs, thrombin, FXa, plasmin, D-dimer, IL-6, and MMP-3 were significantly higher in RA than in OA. In synovial cell experiments, TNF-alpha and thrombin enhanced TF activity on the cell surface, and IL-6, MMP-3, and VEGF secretion were enhanced by thrombin. Increased TF activity, and IL-6, MMP-3, and VEGF secretion induced by thrombin were inhibited by argatroban. In SFs, argatroban inactivated thrombin more effectively than ATIII or HCII. Since thrombin plays an important role in the disease activity of OA and RA, it is a potential therapeutic molecular target. Argatroban was the most effective anticoagulant to inhibit thrombin activity in SF. Intra-articular injection is ideal administration because it can deliver high dose of argatroban without high risk of systematic complication.
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PMID:Argatroban more effectively inhibits the thrombin activity in synovial fluid than naturally occurring thrombin inhibitors. 2726 98