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)

Prekallikrein, plasminogen and prothrombin of human blood plasma have been separately activated by caolin streptokinase and thromboplastin. By measuring the TAME-esterase (N-d Tozy-L-arginine methyl ester) activity of each enzyme and its changes in the course of plasma incubation with the activator, it was possible to estimate the values of precursors of kallikrein, plasmin, thrombin and their inhibitors. Evidence is given that under conditions described the activation is specific of each enzyme and does not affect the level of the two other percursors. The method has been developed in two modifications, permitting to obtain the value of seven parameters in 0.4--0.7 ml of blood plasma.
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PMID:[Method of simultaneous determination of kallikrein, plasmin and thrombin precursors and inhibitors in human blood plasma]. 13 76

Rates of hydrolysis of the newly developed peptide chromogenic substrates S-2160 (N-Bz-Phe-Val-Arg-pNA, HCl), S-2238 (H-D-Phe-Pip-Arg-pNA, 2HCl), S-2222 (N-Bz-Ile-Glu-Gly-Arg-pNA, HCl), and S-2251 (H-D-Val-Leu-Lys-pNA, 2HCl) from AB Kabi Peptide Research and Chromozym TH (Z-Gly-Pro-Arg-pNA, HCl) from Pentapharm Limited were tested against highly purified preparations of human plasmin, bovine trypsin, human alpha thrombin, and bovine factor Xa. S-2160, S-2238, and Chromozym TH are sensitive to thrombin, Chromozym TH and S-2238 exhibiting a substantially greater sensitivity than S-2160. All 3 substrates are insensitive to factor Xa but hydrolyzed to varying degrees by plasmin and trypsin. In contrast, S-2222 is sensitive to Xa and insensitive to thrombin. S-2251 is relatively plasmin-specific, being resistant to the clotting enzymes thrombin and Xa. S-2251 exhibits even greater sensitivity to the SK-plasmin complex than to plasmin. In addition, the substrate Chromozym PK (N-Bz-Pro-Phe-Arg-pNA, HCl) was evaluated and found to be relatively specific for plasma kallikrein. Assays for antithrombin III and heparin using S-2222 as the substrate and factor Xa as the enzyme, plasma plasminogen and plasmin inhibitors using S-2251 as the substrate, and plasma prekallikrein and kallikrein inhibitors using Chromozym PK as the substrate have been developed. Synthetic peptides mimicking amino acid sequences adjacent to proteolytic activation cleavage of plasma serine protease precursors appear to be sensitive and relatively specific tools applicable to kinetical and clinical studies of these enzymes and their inhibitors.
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PMID:Serine protease specificity for peptide chromogenic substrates. 14 72

A purified preparation of bovine thrombokinase (activated Factor X) loses the ability to hydrolyze TAME (p-toluenesulfonyl-L-arginine methyl ester) when it is incubated at 37 degrees in 0.25 M Tris. HCl buffer, pH 7.4 with lauroxypropyl biguanide, N1, N5-dimethyl, N1-lauroxypropyl biguanide, N1-p-chlorophenethyl, N5-phenethyl biguanide, or N1-methyl, N1-p-chlorobenzyl, N5-o,p-dichlorobenzyl biguanide. Activity is lost much more slowly when 0.15 M NaCl is also present. Lauroxypropyl biguanide is the most potent of the compounds tested, 0.22 mM causing thrombokinase to lose almost all of its activity in about 30 minutes at 37 degrees in pH 7.4 buffered saline. Topical bovine thrombin also loses activity when incubated with either of the lauroxypropyl biguanides but not with the diphenethyl or the dibenzyl compound. Instead, the latter biguanides accelerate thrombin's hydrolysis of TAME. The percent acceleration is not affected or only slightly decreased by the presence of 0.15 M NaCl or KCl, and it is also unaffected by incubating the enzyme with the compounds in buffered saline for 4 to 120 minutes. Purified bovine trypsin is stabilized by both lauroxypropyl and the diphenethyl biguanide when incubated at 37 degrees in pH 7.4 buffered saline for the 60 minute test period but neither compounds has any effect on its rate of hydrolysis of TAME. It is postulated that the enzymes first react rapidly and reversibly with all of the test biguanides and, depending upon the enzyme and the substrate, the rate of hydrolysis of the substrate is unaffected, accelerated or inhibited. The lauroxypropyl biguanides also undergo a second, slower reaction with both thrombokinase and thrombin that produces loss of enzymatic activity. The dibenzyl and diphenethyl biguanides also undergo this second slow reaction with thrombokinase but not with thrombin, and none of the biguanides undergo this second reaction with trypsin.
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PMID:The effects of biguanides on thrombokinase, thrombin and trypsin. 24 90

The development of synthetic inhibitors of thrombin and of related arginine-specific esteroproteases is reviewed. The superiority of bis- and tris-benzamidines over benzamidine is disccussed and related to the presence on the enzyme of secondary binding sites beyond the specificity pocket. It is demonstrated that inhibitors with marked specificity for a single enzyme can be produced, and with the help of such selective compounds it is shown that inhibition of factor Xa is more significant for overall anticoagulant effect than inhibition of thrombin.
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PMID:Current concepts on action of synthetic thrombin inhibitors. 35 Jul 30

1. Incubation of decarboxyfactor X with the factor X-activating enzyme from Russell's Viper venom revealed the generation of amidase activity towards Bz-Ile-Glu-Gly-Arg-pNA, but not of activity in blood coagulation. 2. The rate of activation of both factor X and decarboxyfactor X depends on the ability of the zymogens to bind Ca2+. The relationship between Ca2+ concentration and velocity of the activation reaction is sigmoid in the case of factor X, but hyperbolic with decarboxyfactor X. 3. Activated decarboxyfactor X was purified by powder column electrophoresis. 4. Identical changes of primary structure accompanied the activation of factor X and decarboxyfactor X. Identical molecular weight and common antigenic determinants were found in factor Xa and decarboxyfactor Xa. The amino acid composition was identical except for 12 glutamic acid residues in decarboxyfactor Xa and gamma-carboxyglutamic acid residues in factor Xa. 5. Unlike factor X, activated factor X has a very low electrophoretic mobility in the presence of Ca2+ at pH 8.6. This is probably due to self association of factor Xa under the influence of Ca2+. The electrophoretic mobility of activated decarboxyfactor X is only slightly decreased compared to decarboxyfactor X in the presence of Ca2+.
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PMID:Activation of decarboxyfactor X by a protein from Russell's viper venom. Purification and partial characterization of activated decarboxyfactor X. 41 34

An automated method is presented for the determination of thrombin generation in plasma during activation by thromboplastin. The thrombin generated is allowed to split the chromogenic substrate Tol-Gly-Pro-Arg-pNA yielding p-nitroaniline. The increase in absorbance at 410 nm is recorded. This assay may serve as a specific, precise and fast alternative for the conventional clotting tests: "Prothrombin time" and "Thrombotest".
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PMID:An automated amidolytic assay of thrombin generation: an alternative for the prothrombin-time test. 43 85

Lysosomes (granules) of rabbit PMN leukocytes were extracted with either HCl or H2SO4, and the extracts were chromatographed over Sephadex to separate protein constituents. Some of the low molecular weight cationic proteins homogeneous on SDS PAGE (8% and 12.5% gels) were characterized by electrophoretic mobility in acid gels and by amino acid analysis. A 3,700 dalton polypeptide, rich in arginine and cysteine, prolonged the partial thromboplastin time of normal plasma. In low concentration, this protein shortened the clotting time of pure fibrinogen by thrombin. In high concentration this lysosomal cationic protein precipitated fibrinogen from solution; no fibrinopeptides were released to suggest cleavage of fibrinogen. Fibrinolytic protease activity was detected in crude H2SO4 extracts but not in crude HCl extracts. Two separate plasminogen activators, differing from kallikrein or prekallikrein, were isolated from the H2SO4 lysosomal extract and were partially characterized; neither exhibited proteolytic activity on fibrinogen free of plasminogen.
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PMID:Isolation and characterization of granulocyte lysosomal proteins and study of their effects on the clotting system. 54 40

Twenty peptide-4-methylcoumarin amides (MCA) were newly synthesized and tested as possible substrates for alpha-thrombin, factor Xa, kallikreins, urokinase, and plasmin. These fluorogenic peptides contained arginine-MCA as the carboxyl-terminus. Release of 7-amino-4-methylcoumarin was determined fluorometrically. Of these peptides, the following were found to be specific substrates for individual enzymes: Boc-Val-Pro-Arg-MCA for alpha-thrombin, Boc-Ile-Glu-Gly-Arg-MCA, and Boc-Ser-Gly-Arg-MCA for factor Xa, Z-Phe-Arg-MCA for plasma kallikrein, Pro-Phe-Arg-MCA for pancreatic and urinary kallikreins, and glutaryl-Gly-Arg-MCA for urokinase. Moreover, these peptide-MCA substrates were resistant to plasmin.
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PMID:New fluorogenic substrates for alpha-thrombin, factor Xa, kallikreins, and urokinase. 59 14

A photometric assay procedure for platelet factor 4 is described. The synthetic oligopeptide benzoyl-Ile-Glu-Gly-Arg-p-nitroanilide (S-2222) is used as a substrate. By the action of factor Xa, p-nitroaniline (pNA) is split form the peptide bond. The amount of pNA liberated from S-2222 per minute is in direct relation to the activity of factor Xa. This reaction permits a photometric assay. Addition of heparin to an activation system consisting of plasma, thromboplastin and calcium chloride inhibits development of Xa activity. Since platelet factor 4 neutralizes heparin, its activity can be measured in such a system when all other components are kept at a constant level. Experimental details of the reactions involved and clinical results of the assay in comparison to a clotting method are described.
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PMID:Photometric assay of platelet factor 4 with a chromogenic substrate. 59 49

The factor Xa-sensitive substrate BZ-Ile-Glu-Gly-Arg-p-nitroanilide has been made more sensitive by making ester and amide derivatives of the gamma-carboxyl group of the glutamyl residue. The morpholinyl and piperidyl amides react 2.5 times more rapidly with factor Xa.
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PMID:New chromogenic peptide substrates for factor X. 65 82


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