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:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue factor pathway inhibitor (TFPI) is a protease inhibitor with three tandem Kunitz-type inhibitory domains (K1, K2 and K3), which inhibits coagulation factor Xa via K2 domain and factor VIIa-tissue factor complex via K1 domain. Thus TFPI blocks the initial steps of the extrinsic coagulation pathway. TFPI is present in human plasma in three forms, i.e., an LDL/VLDL-associated form, an HDL-associated form and a free form. But the majority of in vivo TFPI is associated with the vascular endothelial cells. The interaction of TFPI with heparin has been demonstrated. The heparin binding site of TFPI (HBS-1) locates in its C-terminal basic portion. We found another heparin-binding site in K3 domain of TFPI, using each of the three Kunitz domains prepared by the limited cleavage of TFPI and also synthetic peptides mimicking the amino acid sequence of a Kunitz domain. These heparin binding sites of TFPI will play an important role for the association with endothelial cells, interacting with heparin sulphate on the surface. We have established a method to measure TFPI activities of lipoprotein-associated forms and a free form of TFPI in plasma and a method to measure a free form of TFPI antigen. We, then, applied these methods for the analysis of hypercholesterolemic patients. Relationship between plasma TFPI levels and endothelial cells-associated TFPI level will be discussed.
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PMID:Tissue factor pathway inhibitor; its structure, function and clinical significance. 911 30

Hypercoagulability is known to occur in the early phase of hemorrhagic shock. The prolongation of excessive clot formation after recovery from a shock state leads to the formation of microthrombi or disseminated intravascular coagulation which disturbs microcirculation, damaging organ function. The aim of the present study is to investigate the beneficial effect of a synthetic protease inhibitor, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate (nafamostat mesilate), in the attenuation of hypercoagulability in hemorrhagic shock. A model of hemorrhagic shock that simulates the clinical course of injured patients was created in anesthetized dogs. The animals were divided into two groups: a control group (group-C, n = 9) and an experimental group (group-E, n = 9). Animals received saline or 0.2 mg/kg of nafamostat mesilate respectively when their mean arterial pressure declined to 50 mmHg. The serum concentration of hydroxytryptamine (5-HT), prothrombin time (PT), and activated partial thromboplastin time (APTT) were determined as indicators of platelet activity and blood coagulation. In group-C, serum 5-HT was elevated significantly at 60 min after hemorrhagic shock but not so in group-E. The APTT at 30 and 60 min was shorter in group-C than in group-E. The PT at 30 min was also shorter in group-C. Plasma fibrin degradation products (FDP) increased at 60 min after the induction of shock in group-C. The results indicate that inadequate tissue perfusion in shock stimulates blood coagulation and that nafamostat mesilate might be beneficial in decreasing excessive blood coagulation.
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PMID:Nafamostat mesilate, a synthetic protease inhibitor, attenuated hypercoagulability in a canine model of hemorrhagic shock. 911 59

Tissue factor pathway inhibitor (TFPI) is a Kunitz-type plasma protease inhibitor that inhibits factor Xa and the factor VIIa/tissue factor catalytic complex. It plays an important role in feedback inhibition of the coagulation cascade (Broze, Annu Rev Med 46:103, 1995). TFPI has also been used successfully to prevent lethality and attenuate coagulopathic responses in a baboon model of septic shock (Creasey et al, J Clin Invest 91:2850, 1993; and Carr et al, Circ Shock 44:126, 1995). However, the mechanism of reduced mortality in these animals could not be explained merely by the anticoagulant effect of TFPI, because TFPI-treated animals also had a significantly depressed interleukin-6 response. Moreover, inhibition of coagulopathic responses by other anticoagulants has failed to block the organ damage or lethal effect of endotoxic shock (Coalson et al, Circ Shock 5:423, 1978; Warr et al, Blood 75:1481, 1990; and Taylor et al, Blood 78:364, 1991). We show here that recombinant TFPI can bind to endotoxin in vitro. This binding prevents interaction of endotoxin with both lipopolysaccharide binding protein and CD14, thereby blocking cellular responses.
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PMID:Tissue factor pathway inhibitor blocks cellular effects of endotoxin by binding to endotoxin and interfering with transfer to CD14. 919 48

Tissue factor (TF), a transmembrane glycoprotein, forms a high affinity complex with factor VII/VIIa (FVIIa) and thereby initiates blood coagulation. Tissue factor pathway inhibitor (TFPI) is an endogenous protease inhibitor of TF/FVIIa-initiated coagulation. We previously reported that TF was a strong chemotactic factor for cultured vascular smooth muscle cells (SMCs). In this study, we examined the contribution of FVIIa and the effect of TFPI to TF-induced cultured SMC migration. TF/FVIIa complex showed a strong migration ability, however, neither TF alone nor FVIIa induced SMC migration. TF/FVIIa treated by a serine protease inhibitor and the complex of TF and inactivated FVIIa (DEGR-FVIIa) did not stimulate SMC migration. Pretreatment with hirudin and the antibodies to alpha-thrombin and factor X had no effect on TF/FVIIa-induced SMC migration, although alpha-thrombin and factor Xa also induced SMC migration respectively. TFPI markedly inhibited TF/FVIIa-induced SMC migration in a concentration-dependent manner, but did not affect the SMC migration induced by platelet-derived growth factor (PDGF)-BB, basic fibroblast-growth factor (bFGF), or alpha-thrombin. These results indicate that the catalytic activity of TF/FVIIa complex is important on SMC migration, and TFPI can reduce SMC migration as well as thrombosis.
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PMID:Tissue factor pathway inhibitor inhibits aortic smooth muscle cell migration induced by tissue factor/factor VIIa complex. 930 67

The three-dimensional structure of antistasin, a potent inhibitor of blood coagulation factor Xa, from the Mexican leech Haementeria officinalis was determined at 1.9 A resolution by X-ray crystallography. The structure reveals a novel protein fold composed of two homologous domains, each resembling the structure of hirustasin, a related 55-residue protease inhibitor. However, hirustasin has a different overall shape than the individual antistasin domains, it contains four rather than two beta-strands, and does not inhibit factor Xa. The two antistasin domains can be subdivided into two similarly sized subdomains with different relative orientations. Consequently, the domain shapes are different, the N-terminal domain being wedge-shaped and the C-terminal domain flat. Docking studies suggest that differences in domain shape enable the N-terminal, but not C-terminal, domain of antistasin to bind and inhibit factor Xa, even though both have a very similar reactive site. Furthermore, a putative exosite binding region could be defined in the N-terminal domain of antistasin, comprising residues 15-17, which is likely to interact with a cluster of positively charged residues on the factor Xa surface (Arg222/Lys223/Lys224). This exosite binding region explains the specificity and inhibitory potency of antistasin towards factor Xa. In the C-terminal domain of antistasin, these exosite interactions are prevented due to the different overall shape of this domain.
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PMID:X-ray structure of antistasin at 1.9 A resolution and its modelled complex with blood coagulation factor Xa. 931 76

We have recently shown that a complex formation of tissue factor pathway inhibitor (TFPI) and factor Xa (Xa) promotes a clearance of proteoglycans-associated TFPI. In the current studies, the interaction between human recombinant TFPI (h-rTFPI) and Xa were kinetically analyzed by utilizing both a protease inhibitor, p-(amidophenyl) methanesulfonyl fluoride hydrochloride, and a specific enzyme-linked immunosorbent assay for the complex of h-rTFPI with Xa. We further investigated the effect of antithrombin III on the complex formation between h-rTFPI and Xa. We found that the h-rTFPI/Xa complex formed in a time-dependent manner: the second-order rate constant (K1) for the complex formation was calculated to be 0.86x10(6) M(-1)s(-1). The addition of antithrombin III to the h-rTFPI solution modestly reduced the rate of the complex formation between h-rTFPI and Xa. Heparin strikingly enhanced antithrombin III's inhibition of Xa and resulted in complete abrogation of the complex formation between h-rTFPI and Xa in the absence or presence of acidic phospholipids. Furthermore, antithrombin III induced dissociation of the preformed h-rTFPI/Xa complex in the presence of heparin. These results suggest that in the presence of heparin, antithrombin III interferes with the catabolism of TFPI mediated via Xa.
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PMID:A kinetic analysis of the interaction of human recombinant tissue factor pathway inhibitor with factor Xa utilizing and immunoassay and the effect of antithrombin III/heparin on the complex formation. 965 Nov 45

A serine-protease inhibitor of plasma kallikrein was screened and purified from a native Korean leech species, Hirudo nipponia. The peptide, named piguamerin, potently inhibited plasma and tissue kallikreins, and trypsin. Sequence analyses by automated Edman degradation revealed 48 amino acid residues and a molecular mass for the peptide of 5090 Da. Piguamerin is similar to antistasin-type inhibitors with the same spacing of ten cysteine residues, but shows differences from hirustasin, antistasin and ghilanten at the residues surrounding Arg27, which is a common P1 reactive residue for these inhibitors. The purified inhibitor modulated plasma clotting in tests of activated partial thromboplastin time at nanomolar concentrations. The serine-protease inhibitor of this leech may be involved in leech hematophagia.
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PMID:Amino acid sequence of piguamerin, an antistasin-type protease inhibitor from the blood sucking leech Hirudo nipponia. 968 84

We purified a new trypsin-chymotrypsin inhibitor, designated tessulin, from the rhynchobdellid leech Theromyzon tessulatum. This 9-kDa peptide was purified to apparent homogeneity by gel-permeation and anion-exchange chromatographies followed by reverse-phase HPLC. The structure of tessulin was determined by reduction, S-beta-pyridylethylation, trypsin digestion, automated Edman degradation and matrix-assisted laser desorption mass spectrometry (m/z 8985 Da). The 81-amino-acid peptide possesses 16 cysteines and exhibits a 16% sequence similarity with antistasin-type inhibitors. Tessulin inhibits trypsin (Ki 1 pM) and chymotrypsin (Ki 150 pM) and exhibits no activity with thrombin, factor Xa, cathepsin G and elastase. This is the first trypsin-chymotrypsin inhibitor isolated from leeches that does not inhibit elastase or cathepsin G, except for cytin and therin. Furthermore, tessulin, in conjunction with other serine-protease inhibitors isolated from Theromyzon (therin, theromin), significantly diminishes the level of human granulocyte and monocyte activation induced by lipopolysaccharides (10 microg). The combined level of inhibition is higher than that of aprotinin, another serine-protease inhibitor used biomedically. Thus, tessulin may be clinically significant in reducing inflammatory events.
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PMID:Amino-acid-sequence determination and biological activity of tessulin, a naturally occurring trypsin-chymotrypsin inhibitor isolated from the leech Theromyzon tessulatum. 987 32

The objective of this study was to determine whether a thrombin inhibitor (PPACK) and a factor Xa inhibitor (GGACK) either alone or in combination can anticoagulate whole blood without biasing the analysis of several critical care analytes. Whole blood clot time was used to assess anticoagulant efficacy. The analytical biases mediated by the anticoagulants on glucose, urea, creatinine, electrolytes, amylase, lactate dehydrogenase, creatine kinase, ionized calcium and pH were assessed. The protease inhibitor mixture (100 micrommol/l PPACK + 500 micromol/l GGACK) was more a potent anticoagulant than the individual agents at the same concentrations. Both PPACK and GGACK, alone and in combination, reduced the activity of creatine kinase and amylase by 3-10% while the remaining critical care analytes were less affected. In conclusion, PPACK and GGACK mixtures can effectively anticoagulate whole blood, but the mixtures exert pre-analytical influences that limit the analytical versatility of these novel plasma-matrices.
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PMID:Evaluation of the thrombin inhibitor D-phenylalanyl-L-prolyl-L-arginine chloromethylketone (PPACK) with the factor Xa inhibitor 1,5-dansyl-L-glutamyl-L-glycyl-L-arginine chloromethylketone (GGACK) as anticoagulants for critical care clinical chemistry specimens. 1009 May 27

Synthetic peptides (5 to 14 amino acids), identical in sequence to the new amino-terminus of the thrombin receptor generated following cleavage by thrombin, act as thrombin receptor agonist peptides. Whilst thrombin receptor antagonist peptides are known, non-peptide thrombin receptor antagonists have yet to be described. In the present study, we compared the antiplatelet effects of 3-(4-chlorophenyl)-2-(2,4-dichlorobenzoylimino)-5-(methoxycarbonyl methylene)-1,3-thiazolidin-4-one (FR171113), a novel non-peptide thrombin receptor antagonist, with the known thrombin receptor antagonist 3-mercapto-propionyl-Phe-Cha-Cha-Arg-Asn-Pro-Asn-Asp-Lys-Tyr-OH (C186-65), and argatroban, a specific protease inhibitor of thrombin. FR171113 and C186-65 inhibited thrombin-induced platelet aggregation (IC(50)=0.29 microM and 15 microM, respectively) and Ser-Phe-Leu-Leu-Arg-Asn-NH(2) [a synthetic thrombin receptor agonist peptide (TRAP-6)] induced platelet aggregation (0.15 microM and 20 microM, respectively) in human washed platelets. Argatroban potently inhibited thrombin-induced platelet aggregation (IC(50)=3.5 nM), but did not inhibit TRAP-6-induced aggregation even at 100 microM. In contrast, these compounds did not show inhibitory effects on ADP- and collagen-induced aggregation in human platelet-rich plasma even at 100 microM. FR171113 caused a parallel shift to the right of the concentration-response curve describing aggregation induced by TRAP-6. The Schild plot of the data had a slope of -0.840 (r=0.98) and the pA(2) was 7.29. In protease activity studies using a chromogenic substrate, argatroban inhibited thrombin protease activity in a dose-dependent manner, whereas FR171113 and C186-65 were inactive, even at 100 microM. Additionally, only argatroban displayed dose-dependent prolongation of thrombin time, activated partial thromboplastin time and prothrombin time. FR171113 and C186-65 showed no effects, even at a concentration of 100 microM. These results suggest that FR171113 has a similar mode of action to C186-65, but with more potent antiplatelet activity. In conclusion, FR171113 is suggested to be the first example of a non-peptide thrombin receptor antagonist.
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PMID:In vitro antiplatelet profile of FR171113, a novel non-peptide thrombin receptor antagonist. 1061 42


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