Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.68 (tissue plasminogen activator)
11,311 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Total fibrinolytic activity in the vasculature is finely tuned by the balance between tissue plasminogen activator and plasminogen activator inhibitor type 1 (PAI-1). Although PAI-1 targets plasminogen activators, it also reacts with other serine proteases such as thrombin and factor Xa. The latter was shown to interact with PAI-1 only when a physiological concentration of calcium ions (Ca++) is present. Through such interaction, thrombin and Ca++-bound factor Xa shortened fibrin clot lysis times in a purified system by neutralizing PAI-1 activity. Both unfractionated heparin and vitronectin were shown to enhance the clot lysis further. Together with the cleavage and inactivation of PAI-1 by human neutrophil elastase, which was reported previously from our laboratory, such neutralization of PAI-1 activity by these serine proteases was shown to be strongly involved in the coagulation-associated enhancement of fibrinolytic activity.
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PMID:Coagulation-associated enhancement of fibrinolytic activity via a neutralization of PAI-1 activity. 1080 80

A method is presented for the preparation and use of fluorogenic peptide substrates that allows for the configuration of general substrate libraries to rapidly identify the primary and extended specificity of proteases. The substrates contain the fluorogenic leaving group 7-amino-4-carbamoylmethylcoumarin (ACC). Substrates incorporating the ACC leaving group show kinetic profiles comparable to those with the traditionally used 7-amino-4-methylcoumarin (AMC) leaving group. The bifunctional nature of ACC allows for the efficient production of single substrates and substrate libraries by using 9-fluorenylmethoxycarbonyl (Fmoc)-based solid-phase synthesis techniques. The approximately 3-fold-increased quantum yield of ACC over AMC permits reduction in enzyme and substrate concentrations. As a consequence, a greater number of substrates can be tolerated in a single assay, thus enabling an increase in the diversity space of the library. Soluble positional protease substrate libraries of 137, 180 and 6,859 members, possessing amino acid diversity at the P4-P3-P2-P1 and P4-P3-P2 positions, respectively, were constructed. Employing this screening method, we profiled the substrate specificities of a diverse array of proteases, including the serine proteases thrombin, plasmin, factor Xa, urokinase-type plasminogen activator, tissue plasminogen activator, granzyme B, trypsin, chymotrypsin, human neutrophil elastase, and the cysteine proteases papain and cruzain. The resulting profiles create a pharmacophoric portrayal of the proteases to aid in the design of selective substrates and potent inhibitors.
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PMID:Rapid and general profiling of protease specificity by using combinatorial fluorogenic substrate libraries. 1086 34

We evaluated the effectiveness, ease of use and safety of five machines for blood salvage during coronary artery surgery. All were equally effective in concentrating red cells. We measured haemoglobin, packed cell volume, free haemoglobin, white cells, neutrophil elastase, platelets, thrombin-antithrombin complex (TAT), prothrombin activation peptide F1.2, fibrin degradation product (d-dimers), tissue plasminogen activator (tPA) and heparin in wound blood, in washed cell suspensions and in a unit of bank blood prepared for each patient. All machines were equally safe and easy to use and were equally effective in removing heparin and the physiological components measured. There were no adverse effects on patients. Clotting factors are severely depleted both in salvaged blood, even before washing, and in bank blood. Cell savers are a valuable adjunct to coronary artery surgery, but careful monitoring of coagulation is required when the volumes of either bank blood or salvaged blood are large.
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PMID:Study of five cell salvage machines in coronary artery surgery. 1207 73

Polymorphonuclear leucocytes (PMN) are important in the resolution of human thrombi, with u-PA as a key player. We have shown that the u-PA activity of PMN depends on the presence of plasma; the study presented here provides an explanation for that requirement. Here we show that PMN degraded scu-PA and also tcu-PA, t-PA and plasmin, resulting in loss of fibrinolytic activity. Plasma protected against this degradation; alpha1-antitrypsin was identified as a protective factor. Purified human neutrophil elastase mirrored the effects of PMN, again neutralized by plasma inhibitors. These findings illustrate the dual role of PMN in the breakdown of thrombi, in that they contribute both u-PA, which lyses fibrin, and other proteases, including elastase, which can cleave fibrin and plasminogen activators/plasmin. Similarly, plasma can potentiate fibrinolysis by neutralization of PMN elastase, in addition to direct inhibition of fibrinolytic proteases. Our previous studies show that PMN in thrombi are mostly pro-fibrinolytic; the anti-fibrinolytic role defined here may be important in other pathologies where fibrin persists.
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PMID:Polymorphonuclear leucocytes have two opposing roles in fibrinolysis. 1208 79

Because of its structural homology with plasminogen, the apolipoprotein(a) [apo(a)] component of the athero-thrombogenic lipoprotein(a) [Lp(a)] particle inhibits plasminogen binding and activation onto fibrin as well as the subsequent fibrinolysis. In a similar manner, apo(a) may also interfere with plasmin(ogen)-induced cell detachment and apoptosis of adherent cells. To investigate this hypothesis, we studied the effect of a recombinant apo(a) [r-apo(a)] on plasminogen activation-induced apoptosis of vascular smooth muscle cells (VSMCs) and fibroblasts-like CHO-K1 cells. We demonstrate for the first time that apo(a) displays a concentration-dependent biphasic, enhancing/preventing effect on plasmin(ogen) induced cell detachment of VSMCs and CHO-K1 cells. Our results show that r-apo(a) binds to these cells with higher affinity than plasminogen [K(d) = 0.9 +/- 0.2 microM for plasminogen, K(d) = 1.77 +/- 0.34 nM for r-apo(a)] in a lysine-dependent manner. At high r-apo(a)/plasminogen ratios, their competitive interaction results in a partial inhibition of plasminogen activation by cell-bound t-PA. As a consequence, r-apo(a) prevents plasmin(ogen)-induced cell detachment and apoptosis. Surprisingly, at low r-apo(a)/plasminogen ratios, an enhancement in plasmin(ogen)-induced cell detachment and apoptosis was observed. This effect was shown to be "plasmin-selective" as r-apo(a) was unable to potentiate cell detachment induced by human neutrophil elastase and trypsin. Altogether these data are consistent with a new mechanism of apo(a)/plasmin(ogen) interactions that may contribute to the athero-thrombogenic potential of Lp(a).
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PMID:Dual effect of apolipoprotein(a) on plasmin(ogen)-induced apoptosis through modulation of cell detachment of adherent cells. 1654 73

The honeybee is an important insect species in global ecology, agriculture, and alternative medicine. While chymotrypsin and trypsin inhibitors from bees show activity against cathepsin G and plasmin, respectively, no anti-elastolytic role for these inhibitors has been elucidated. In this study, we identified an Asiatic honeybee (Apis cerana) chymotrypsin inhibitor (AcCI), which was shown to also act as an elastase inhibitor. AcCI was found to consist of a 65-amino acid mature peptide that displays ten cysteine residues. When expressed in baculovirus-infected insect cells, recombinant AcCI demonstrated inhibitory activity against chymotrypsin (K(i) 11.27 nM), but not trypsin, defining a role for AcCI as a honeybee-derived chymotrypsin inhibitor. Additionally, AcCI showed no detectable inhibitory effects on factor Xa, thrombin, plasmin, or tissue plasminogen activator; however, AcCI inhibited human neutrophil elastase (K(i) 61.05 nM), indicating that it acts as an anti-elastolytic factor. These findings constitute molecular evidence that AcCI acts as a chymotrypsin/elastase inhibitor.
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PMID:Anti-elastolytic activity of a honeybee (Apis cerana) chymotrypsin inhibitor. 2320 Aug 35

Kunitz-type serine protease inhibitors are involved in various physiological processes, such as ion channel blocking, blood coagulation, fibrinolysis, and inflammation. While spider-derived Kunitz-type proteins show activity in trypsin or chymotrypsin inhibition and K(+) channel blocking, no additional role for these proteins has been elucidated. In this study, we identified the first spider (Araneus ventricosus) Kunitz-type serine protease inhibitor (AvKTI) that acts as a plasmin inhibitor and an elastase inhibitor. AvKTI possesses a Kunitz domain consisting of a 57-amino-acid mature peptide that displays features consistent with Kunitz-type inhibitors, including six conserved cysteine residues and a P1 lysine residue. Recombinant AvKTI, expressed in baculovirus-infected insect cells, showed a dual inhibitory activity against trypsin (K(i) 7.34 nM) and chymotrypsin (K(i) 37.75 nM), defining a role for AvKTI as a spider-derived Kunitz-type serine protease inhibitor. Additionally, AvKTI showed no detectable inhibitory effects on factor Xa, thrombin, or tissue plasminogen activator; however, AvKTI inhibited plasmin (K(i) 4.89 nM) and neutrophil elastase (K(i) 169.07 nM), indicating that it acts as an antifibrinolytic factor and an antielastolytic factor. These findings constitute molecular evidence that AvKTI acts as a plasmin inhibitor and an elastase inhibitor and also provide a novel view of the functions of a spider-derived Kunitz-type serine protease inhibitor.
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PMID:A spider-derived Kunitz-type serine protease inhibitor that acts as a plasmin inhibitor and an elastase inhibitor. 2330 98

Sepsis, defined as infection-induced systemic inflammatory response syndrome, invariably leads to hemostatic abnormalities ranging from insignificant coagulopathy to disseminated intravascular coagulation (DIC). The inflammation-induced activation of coagulation, the downregulation of physiologic anticoagulant pathways, and impairment of fibrinolysis play a pivotal role in the pathogenesis of microvascular fibrin thrombosis and multiple organ dysfunction syndrome (MODS) in DIC associated with sepsis. The balance between tissue plasminogen activator and plasminogen activator inhibitor-1 mainly regulates fibrinolytic activity. Thrombin-activatable fibrinolysis inhibitor and neutrophil elastase also modulate fibrinolysis. Dynamic changes in these molecules are deeply involved in the pathomechanisms of the impairment of fibrinolysis, leading to MODS in DIC associated with sepsis. Evidence indicates that physical entrapment of bacteria by fibrin at the site of infection may limit their capacity to disseminate into nearby tissues, organs, and systemic circulation. Under this circumstance, impairment of fibrinolysis has protective role in the host defense. Given the protective and pathologic potential of fibrinolysis during sepsis, therapeutics that control DIC as a systemic syndrome, while maintaining the host defense at the infectious foci, are required for the protection against both the development of MODS and for the host defense mechanisms.
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PMID:Role of fibrinolysis in sepsis. 2344 14

Spider-derived Kunitz-type serine protease inhibitors have been shown to exhibit plasmin and elastase inhibition activity and potassium channel blocking activity, but thus far, no additional roles for spider-derived chymotrypsin inhibitors have been elucidated. In this study, a spider (Araneus ventricosus) chymotrypsin inhibitor (AvCI) that acts as an elastase inhibitor and a microbial serine protease inhibitor was identified. AvCI is a 70-amino acid mature peptide that displays eight conserved cysteine residues and a P1 lysine residue. Recombinant AvCI expressed in baculovirus-infected insect cells demonstrated inhibitory activity against chymotrypsin (Ki 49.85 nM), but not trypsin, which defines a role for AvCI as a spider-derived chymotrypsin inhibitor. AvCI also exhibited inhibitory activity against microbial serine proteases such as subtilisin A (Ki 20.51 nM) and proteinase K (Ki 65.42 nM). Furthermore, AvCI exhibited no detectable inhibitory effects on factor Xa, thrombin, tissue plasminogen activator, or plasmin; however, AvCI strongly inhibited human neutrophil elastase (Ki 8.74 nM) and porcine pancreatic elastase (Ki 11.32 nM), indicating that AvCI acts as an anti-elastolytic factor. These findings constitute molecular evidence that AvCI acts as an inhibitor against chymotrypsin, microbial serine proteases, and elastases. This paper provides a novel view of the functions of a spider-derived chymotrypsin inhibitor.
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PMID:A spider (Araneus ventricosus) chymotrypsin inhibitor that acts as an elastase inhibitor and a microbial serine protease inhibitor. 2349 42

Thrombolysis is recommended for reperfusion following acute ischemic stroke (AIS), but its effects on stroke-associated injury remain to be clarified. Here, we investigated the effects of recombinant tissue plasminogen activator (r-tPA) on neutrophil pathophysiology in vitro and in a case-control study with AIS patients submitted (n=60) or not (n=30) to thrombolysis. Patients underwent radiological and clinical examination as well as blood sampling at admission and after 1, 7 and 90days. In vitro, 30-min incubation with 0.1-1 mg/ml r-tPA induced neutrophil degranulation in different substrate cultures. Pre-incubation with kinase inhibitors and Western blot documented that degranulation was associated with activation of PI3K/Akt and ERK1/2 pathways in Teflon dishes and PI3K/Akt in polystyrene. In thrombolysed patients, a peak of neutrophil degranulation products (matrix metalloproteinase [MMP]-9, MMP-8, neutrophil elastase and myeloperoxidase), was shown during the first hours from drug administration. This was accompanied by serum augmentation of protective tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. An increased rate of haemorrhagic transformations on day 1 after AIS was shown in thrombolysed patients as compared to non-thrombolysed controls. In conclusion, r-tPA treatment was associated with in vitro neutrophil degranulation, indicating these cells as potential determinants in early haemorrhagic complications after thrombolysis in AIS patients.
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PMID:Treatment with recombinant tissue plasminogen activator (r-TPA) induces neutrophil degranulation in vitro via defined pathways. 2553 Jan 54


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