Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.5 (thrombin)
 33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of pH and time on the stability of heparin sodium in dextrose 5% in water (D5W) injection and in dextrose 5% in 0.45% sodium chloride injection was studied. Admixtures of heparin sodium 5,000 units/250 ml were tested after 0, 10, 20 and 30 minutes and 1, 2, 6, 12 and 24 hours of storage at room temperature. The pH of the carrier solutions was adjusted to 2, 4 or 9 prior to adding the heparin sodium. Heparin activity was measured using a thrombin clotting time assay. Samples were tested for pH changes at the same times. No substantial changes in heparin activity over the 24-hour period occurred with any of the pH-adjusted solutions. The pH of the heparin-D5W admixtures remained constant over time. The two carrier solutions, over a pH range of 2 to 9, appear to be suitable vehicles for heparin sodium.
 ...
PMID:Effect of pH on the stability of heparin in 5% dextrose solutions. 3 53

A high molecular weight glycoprotein consisting of three disulfide-linked 142,000 molecular weight chains has been isolated from human blood platelets. The glycoprotein, designated thrombospondin, is released by platelets in response to thrombin treatment and is proteolyzed when left in the presence of platelets after liberation. It is relatively insensitive to degradation by thrombin. Thrombospondin is a filamentous protein of dimensions approximately 7 X 70 nm and contains 1.9% neutral sugars, 1.4% amino sugars, 0.7% sialic acid, and no hexuronic acid. Amino acid analysis reveals that the level of cysteine is approximately 260 residues per molecule. Thrombospondin binds to immobilized heparin but is released by 0.45 M sodium chloride. A single band is obtained by isoelectric focusing, indicating a pI of 4.7 as well as a relatively high degree of purity. Degradation of the intact molecule with trypsin yields a stable core particle of molecular weight 210,000 comprised of three 70,000 chains.
 ...
PMID:Isolation and characterization of a high molecular weight glycoprotein from human blood platelets. 10 49

Neither normal nor hemophilic factor VIII protein enters a 5% sosium dodecyl sulfate gel; on reduction, however, a single 195 000-molecular-weight peptide is observed. Hemophilic and normal factor VIII contain carbohydrate and appear identical in subunit molecular weight, electrical charge, and major antigenic determinants. Thrombin activation and inactivation of factor VIII does not detectably change the subunit molecular weight. Trypsin causes similar activity changes and obviously cleaves the factor VIII subunit. Human plasmin destroys factor VIII procoagulant activity and degrades the factor VIII subunit to 103 000-, 88 000-, and 17 000-molecular-weight peptides. Both normal and hemophilic factor VIII as well as thrombin-inactivated factor VIII support ristocetin-induced platelet aggregation. Purified factor VIII chromatographed on 4% agarose in 1.0 M sodium chloride shows no dissociation of the procoagulant activity from the void volume protein. Gel chromatography on 4% agarose in 0.25 M calcium chloride results in a procoagulant activity peak removed from the void volume protein; both peaks contain protein which does not enter a 5% SDS gel, but on reduction a 195 000-molecular-weight subunit band is observed for each. Both the void volume protein peak and the procoagulant activity peak from the 0.25 M calcium chloride-agarose gel column support ristocetin-induced platelet aggregation. After removal of calcium, a small amount of procoagulant activity is present only in the void volume peak. These data suggest that both the procoagulant and von Willebrand activities are on the same molecule. Thus our previous conclusion remains the same: human factor VIII is a large glycoprotein composed of identical 195 000-molecular-weight subunits jointed by disulfide bonds and is responsible for both antihemophilic and von Willebrand activities in human plasma.
 ...
PMID:Molecular structural studies of human factor VIII. 12 89

Perfusion of thrombin and trypsin solutions through the frog carotid labyrinth acts on the carotid chemoreceptors and evokes reflex response of the anticoagulating system. The similarity of effects of both these agents seems to be due to similarity of their structures. Other agents acting on the frog vascular chemoreceptors: sodium chloride hypoxia, lobeline,--cause no activation of the reflex anticoagulating system. Thrombin is concluded to be the adequate and specific irritant of the vascular chemoreceptors of the frog anticoagulating system.
 ...
PMID:[Specificity of the effect of thrombin on the chemoreceptors of the frog carotid labyrinth]. 30 Nov 3

Thrombin binds with high affinity to specific cell-surface receptors on washed human platelets. We present experiments indicating that thrombin binding correlates withe the release reaction when binding is perturbed by anions. Marked differences in the affinity of human 125I-thrombin for platelets wer observed in various isotonic buffers at pH 7.4. At low concentrations of thrombin (0.001-0.01 U/ml), binding was 5-fold greater in Tris-sodium acetate and 12-fold greater in Tris-sodium cacodylate than in Tris-sodium chloride. These anion-induced changes in 125I-thrombin binding paralleled changes in [14C] serotonin release when both parameters were measured in the same platelets. Thus, equivalent release occurred for equal amounts of thrombin bound in all buffers, even though the thrombin concentration varied by up to 30-fold. After approximately 100 molecules of thrombin bound per platelet, complete release occurred in all buffers in 2 min. The effect of anions was specific for the thrombin-receptor interaction as there was no corresponding effect on the binding of erythroagglutinating phytohemagglutinin (E-PHA) to platelets nor on E-PHA or collagen-induced serotonin release. The various anions did not alter platelet morphology as judged by electron microscopy. The anions had no effect on thrombin esterase catalytic activity. In addition, the total number of thrombin receptors per platelet was approximately the same in all buffers. Thus anions alter the affinity between platelet thrombin receptors and a site on thrombin distinct from the catalytic site. We conclude that the thrombin receptor is essential for thrombin-induced platelet reactions.
 ...
PMID:The perturbation of thrombin binding to human platelets by anions. 115 95

Glycerol increased the transition temperature (Tm) of thrombin in a concentration-dependent fashion up to a concentration of 50% glycerol in aqueous buffer solution. Glycerol showed a comparable effect on Tm of trypsin. This effect on Tm of thrombin was not seen in the presence of excess sodium chloride (1.2 M) in aqueous buffer solution. The stabilizing effect of glycerol may be due to increased energy demand to unfold the protein molecule, as reflected by an increase in Tm. This stabilizing effect, as measured by Tm, was seen for other polyols, including sucrose, and was also dependent on the concentration of the stabilizing agent. Microcalorimetry may be used as an effective tool to screen for the protective action of compounds in enzyme stabilization studies before conducting the time-consuming and expensive stability studies of proteins in the presence of additives under different storage conditions.
 ...
PMID:Enhancement of the stability of thrombin by polyols: microcalorimetric studies. 135 42

The purpose of this randomized crossover study was to determine whether nitroglycerin interacts with heparin in terms of its anticoagulative properties as determined by activated partial thromboplastin time and thrombin time. Eight healthy adults were given either a 60-minute intravenous infusion of 5 mg of nitroglycerin or a 0.9% sodium chloride solution subsequent to the administration of an intravenous injection of 5000 U of heparin. No nitroglycerin-related drug interference with heparin was observed as measured by the activated partial thromboplastin time and the thrombin time.
 ...
PMID:Absence of drug interaction between heparin and nitroglycerin. Randomized placebo-controlled crossover study. 212 Nov 14

At present the preparations of fibrin glue used a thrombin from equine or bovine origin. In order to remove the problems of antigenicity we developed a method of purification from acidified plasma. We used one affinity chromatography on benzamidine-Spherodex and compared three methods of elution: non specific (sodium chloride gradient) and biospecific competitors (arginin methylester or benzamidin). The yield is evaluated between 64 and 84% and the purification factor close to 160. The obtained thrombin is better than animal thrombin in the preparations of fibrin glue.
 ...
PMID:[Isolation of human thrombin by affinity chromatography with silicate to be used in the preparation of biological glue]. 227 69

Biological glue is obtained by mixing different specific plasma proteins including a serine protease, thrombin. Surprisingly at present the thrombin used in such a mixture is from equine or bovine origin while all other components are from human. In this paper we described a particular efficient and specific chromatographic method for the purification of human thrombin usable as a serine protease in the preparation of biological glue. A pure and active thrombin is obtained from a plasma fraction after adsorption on benzamidine-Spherodex followed by an elution with non specific (sodium chloride gradient) or biospecific competitors (arginine methylester or benzamidine). The obtained thrombin with a yield close to 80% and a purification factor close to 160, showed good properties in the replacement of animal thrombin in the condition of biological glue.
 ...
PMID:[Purification of human thrombin by affinity chromatography for its use in preparations for biological coagulation]. 261 44

Cross-linked polystyrenes modified with L-arginyl methyl ester mimic the binding site of antithrombin III and thrombin substrates. They can be used as stationary phases in high-performance affinity chromatography of thrombin. Under isocratic conditions, thrombin is strongly adsorbed on the resins when the sodium chloride concentration is lower than 0.5 M. The bound enzyme can be selectively desorbed when the salt concentration is raised to about 1.2 M. With a linear salt gradient, the specific elution of thrombin can be effected with a high recovery of its enzymatic activity. The decomposition products of thrombin, when treated with sodium dodecyl sulphate, are not retained by the stationary phase. The effects of the flow-rate and salt gradient slope on the adsorption and desorption of alpha-thrombin demonstrate the importance of kinetic parameters.
 ...
PMID:High-performance affinity chromatography of human thrombin on modified polystyrene resins. 373 36


1 2 3 Next >>