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:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Three components with arginine esterase activities were found in the venom of the Chinese pit viper (Agkistrodon halys Pallas). They were identified as bradykinin releasing, thrombin-like and fibrinogenolytic enzymes respectively. The thrombin-like enzyme of A. halys Pallas was purified to a homogeneous state. It was a glycoprotein with molecular weight of about 43,000. Though this enzyme displayed a higher esterase activity on BAEE than trypsin and human thrombin, it showed very weak clotting ability on fibrinogen. The kinetic analysis of the release of fibrinopeptides A (FPA) and B (FPB) showed that the action mode of this enzyme on fibrinogen was just opposite to that of mammalian thrombin. FPB was first released, followed by FPA after a long lag period.
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PMID:Study on the thrombin-like enzyme preferentially releasing fibrinopeptide B from the snake venom of Agkistrodon halys Pallas. 646 61

At pH 4.1, bovine thrombin reacts rapidly with N-bromo-succinimide to yield modified enzyme containing oxidized tryptophan residue. Both fibrinogen clotting activity and esterase activity are reduced considerably when three moles of tryptophan residues per mole of thrombin are oxidized, but the Michaelis constants for synthetic substrates are not appreciably altered. Reaction of NBS also results in a decrease in the affinity of thrombin for heparin. The dissociation constant for heparin-thrombin complex is increased by 2.6-fold due to the modification of one tryptophan residue. However, the magnitude of the increase in the dissociation constant remains the same for modified enzymes containing approximately two or three oxidized tryptophan residues. The rate constant for the inactivation of thrombin by antithrombin III is increased by 2.5-fold due to the modification of a single tryptophan residue. This increase in rate constant is not further amplified when more than one tryptophan residue is oxidized. In contrast, in the presence of heparin the rate of inactivation of modified and unmodified thrombins by antithrombin III are not significantly different. Thus, the heparin-sensitized inactivation of thrombin by antithrombin III is affected by the modification of one tryptophan residue. Spectrophotometric titrations of the phenolic hydroxyl groups suggest that the structural environments of tyrosyl groups for both unmodified and modified thrombin containing one oxidized tryptophan residue, are similar. The temperature for half loss of catalytic activity of control and NBS-modified thrombin, containing one oxidized tryptophan, are 52 and 51.5 degrees C respectively. It appears that the one tryptophan residue of thrombin is situated at or close to the binding site of heparin.
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PMID:Catalytic and regulatory functions of N-bromosuccinimide-modified bovine thrombin. 652 42

Ovalbumin is partially homologous in sequence with the proteinase inhibitors alpha 1-proteinase inhibitor and anti-thrombin III. The region of sequence in ovalbumin which corresponds to the reactive sites of these proteinase inhibitors is susceptible to attack by subtilisin, elastase, thermolysin, bromelain, and Bacillus cereus protease. The esterase activity of elastase is not inhibited by ovalbumin, but ovalbumin is efficiently cleaved by elastase. In contrast with these proteases, trypsin does not cleave ovalbumin.
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PMID:Ovalbumin is an elastase substrate. 656 26

A study was made of the interaction between prothrombin and enzymes: blood plasma kallikrein and factors alpha-XIIa and beta-XIIa immobilized on enzacryl-AH. Kallikrein-induced prothrombin proteolysis was accompanied by a decrease in prothrombin activity, appearance of BAME-esterase and poor clotting activity. As a result of fractionation of products on the column with DEAE-Sephadex A-50, some fractions that have thrombin amidase activity (splitting of the substrate S-2238) and high antithrombin activity were obtained. Antithrombin activity manifested in the inhibition of fibrinmonomer aggregation during fibrin formation. During incubation with prothrombin, factors alpha-XIIa and beta-XIIa also stimulated the appearance of BAME-esterase activity. None of the immobilized enzymes activated factor X.
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PMID:[Prothrombin--substrate for blood plasma kallikrein and factor XIIa]. 660 74

A biologic tissue adhesive, a two-component fibrin sealant, for the immobilization of experimentally produced osteochondral fractures of the radial head and femoral condyle was investigated in dogs. The two components of the fibrin sealant were a sealer protein solution (fibrinogen) and a thrombin solution. A fibrinolytic inhibitor (C-esterase inhibitor) was added to prevent degradation of the fibrin by proteolytic enzymes. The operation was performed in 16 joints in four dogs. Control fractures on the right side were fixed with 5-cm Kirschner wires. No external immobilization was utilized. The dogs were killed at intervals of two, four, and eight weeks. There were no complications. All fractures healed uneventfully by eight weeks. Osseous repair seemed to be stimulated by the sealant and to occur faster than in the fractures fixed with pins.
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PMID:A fibrin adhesive seal for the repair of osteochondral fracture fragments. 660 48

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

Partial reduction of thrombin disulfide bridges with dithiothreitol in the absence of denaturants inhibits the fibrinogen clotting but not the esterase activity of the enzyme. The clotting activity reappears on spontaneous air reoxidation of thrombin. As a result of the reaction with dithiothreitol, two disulfide bonds are cleaved in thrombin molecule inducing a small decrease of beta-sheets in the secondary structure of thrombin. It may be concluded that this modification does not affect the catalytic site of thrombin but has influence upon the fibrinogen binding (recognition) site.
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PMID:Enzymic activity of thrombin with partially reduced disulfide bonds. 665 11

Dimethyl sulfoxide produces an opposite effect on the esterase and amidase activities of bovine thrombin. The esterase activity is increased by two fold but the amidase activity is decreased to 9% of the initial activity in 20% dimethyl sulfoxide. The stimulation of the esterase activity is due to the change in Vmax rather than Km for the substrate p-Tosyl-L-Arginine methyl ester. The inhibition of the esterase activity of thrombin by NaCl is not affected due to the addition of dimethyl sulfoxide. Ki for NaCl, 0.03 M, is the same for both in the absence and in the presence of 10% dimethyl sulfoxide. The catalytic activity of thrombin is inhibited by heparin. This effect is significantly decreased by dimethyl sulfoxide. The dissociation constant of heparin-thrombin complex, measured in the absence and in the presence of 10% dimethyl sulfoxide are 4 nM and 28 nM respectively. Thermal stability of thrombin, determined by monitoring catalytic activity, is increased in the presence of dimethyl sulfoxide. The enhancement of the fluorescence intensity of thrombin in the presence of dimethyl sulfoxide reflects the contribution of more exposed tryptophanyl residues. The alteration of the conformation of the enzyme structure due to the perturbation of the aqueous medium by dimethyl sulfoxide, has been attributed to these observed effects.
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PMID:The catalytic activity and physical properties of bovine thrombin in the presence of dimethyl sulfoxide. 684 75

Prethrombin 2, and immediate precursor of thrombin, was obtained by limited trypsin or active factor X proteolysis by prethrombin 1. The conversion of prethrombin 1 to prethrombin 2 does not occur in the absence of enzymes. It has been shown that factor V has no influence on the rate of thrombin generation from prethrombin 2 and that prethrombin itself has no coagulant or esterase activity. Intravenous injection of prethrombin 2 preparations led to an increase in plasma recalcification time, overall fibrinolytic activity and non-enzymatic fibrinolysis. In addition, there was observed a considerable increase in fibrinogen-heparin complex activity. The data obtained indicate excitation of the anticoagulant system with intravenous injection of small doses of prethrombin 2.
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PMID:[Activation of the anticoagulant system by prethrombin 2, a thrombin precursor]. 696 43

Thrombin incubated with 2,3-diphosphoglycerate (150 nmol 2,3-DPG/1 NIH thrombin unit) lost up to 70% of its clotting activity, whereas the esterase activity remained unchanged. No fibrinopeptide release by thrombin was observed in the presence of 2,3-DPG. The fibrin polymerization was normal. By chromatography on Amberlite IRC-50, alpha-thrombin was eluted at pH 8.0. In presence of 2,3-DPG, alpha-thrombin was not eluted. Likely, 2,3-DPG can interfere with thrombin.
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PMID:The in vitro inhibitory effect on thrombin by 2,3-diphosphoglycerate. 703 80


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