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 adsorption of 125I-thrombin to polypropylene tubes has been studied with thrombin dissolved in tris-buffered saline (TBS), TBS with 0.66% polyethylene glycol (PEG), and TBS with 0.01% or 0.20% bovine serum albumin (BSA). Adsorption stabilized over time from all three solutions, increased with increasing concentrations of unadsorbed thrombin, and was reversible by repetitive washing. At equilibrium, more thrombin adsorbed from TBS-PEG than from TBS. The difference was attributable to an increased amount of thrombin deposited by evaporation during aspiration of the polypropylene tubes. Adsorption equilibrium and capacity were otherwise relatively unaffected by the presence of PEG. However, PEG was effective in retarding thrombin adsorption by markedly reducing the adsorption rate. Reduction of adsorption in the presence of BSA, on the other hand, was explained by competitive inhibition. Pretreatment of the tubes with PEG or BSA was also shown to be effective in reducing thrombin adsorption from TBS.
 ...
PMID:The adsorption of thrombin to polypropylene tubes: the effect of polyethylene glycol and bovine serum albumin. 398 99

Addition of gamma-globulin, serum albumin, hemoglobin, or ovalbumin in concentrations of 1-10 g/dl to solutions of purified fibrinogen results in a substantial (up to six-fold) decrease in the lag time preceding appearance of a firm fibrin gel following addition of thrombin at 24 degrees C. The effect does not appear to be due to a protein-induced enhancement in the enzymatic activity of thrombin, nor does it appear to be due to the co-condensation of the added protein with fibrin/fibrinogen. It is suggested that the observed effect is primarily due to nonspecific volume exclusion arising from increased fractional occupancy of solution volume by macromolecules.
 ...
PMID:Acceleration of fibrin gel formation by unrelated proteins. 399 34

Addition of two commercial luciferin-luciferase reagents caused marked inhibition of the aggregatory response of washed human platelets to thrombin, ADP, vasopressin and platelet-activating factor (PAF). Analysis of the effects of the individual components of one of these reagents revealed that Mg2+, and to a lesser extent bovine serum albumin, was responsible for the observed inhibition. A modified luciferin/luciferase reagent has been designed on the basis of these data for use in washed platelet suspensions which causes minimal inhibition of the aggregatory and secretory responses to thrombin but which gives a near maximal luminescence yield.
 ...
PMID:Inhibition by luciferin-luciferase reagents of aggregatory responses to excitatory agonists in washed platelet suspensions. 400

Heparin cofactor II (HCII) is a glycoprotein in human plasma which inactivates thrombin rapidly in the presence of heparin or dermatan sulfate. We have developed a functional assay for HCII in which inhibition of thrombin by plasma is determined in the presence of dermatan sulfate. The assay is specific for HCII by the following criteria: (a) under the conditions of the assay, 125I-thrombin forms complexes in plasma which comigrate with the thrombin-HCII complex during sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE); (b) activity detected by the assay is decreased in plasma absorbed with monospecific antibodies against HCII; and (c) purified antithrombin III (ATIII) is unreactive in the assay system. Addition of Polybrene to the assay permits determination of HCII activity in samples containing less than or equal to 12 U/mL of heparin. The range of HCII concentrations in normal individuals is 1.2 +/- 0.4 mumol/L (mean +/- 2 SD, n = 34). HCII activity was determined in 54 consecutive patients undergoing evaluation for the possibility of disseminated intravascular coagulation (DIC). Ten of the 11 patients with documented DIC had decreased HCII activity as compared with only 7 of the 43 patients without DIC (chi 2 = 19.3, P less than .0001). The concentrations of HCII and ATIII varied in parallel in most of the patients tested. A significant correlation between decreased HCII activity and decreased serum albumin concentration was also observed in these patients and in eight additional patients with hepatic failure in the absence of DIC. We conclude that HCII activity is decreased in many patients with DIC and hepatic failure.
 ...
PMID:Heparin cofactor II activity in patients with disseminated intravascular coagulation and hepatic failure. 404 18

The effects of blood plasma and some plasma constituents on several types of thrombin inhibitors were quite varied. Two active esters were rapidly destroyed by serum albumin; one of these reacted initially with Lys-199, the residue that is also acylated by aspirin. Of two sulfonyl fluorides one was unaffected by albumin, and the other bound reversibly to albumin; this binding was greater with albumin acetylated at Tyr-411 near the binding site for medium-chain fatty acids. The effects of a chloromethyl ketone were inhibited, apparently reversibly, by albumin but were practically abolished by glutathione. Of two potent reversible inhibitors one was unaffected by plasma constituents, while the other was over 10-fold less potent in plasma than in fibrinogen. The effect of plasma could be partially explained by binding to albumin and lipoproteins.
 ...
PMID:Studies on the inhibition of human thrombin: effects of plasma and plasma constituents. 617 8

Heparin covalently-linked to polyvinyl alcohol (PVA) is a biomaterial which is of potential value as a non-thrombogenic coating. 125I-labelled thrombin adsorbed to heparin-PVA beads was not dislodged by phosphate-buffered saline, pH 7.4, although radioactivity was progressively displaced from the adsorbent by fibrinogen-free human plasma. Analysis by gel filtration and affinity chromatography showed that the released radioactivity was distributed between (thrombin-antithrombin-III) complex (approx. 70%) and, probably, (thrombin-alpha-2-macroglobulin) complex (approx. 30%). Less efficient thrombin displacement was obtained by either bovine serum albumin (5% w/v) or antithrombin-III-free human plasma: in the latter case, the dislodged enzyme was presumably associated with alpha-2-macroglobulin. Purified alpha-2-macroglobulin did not displace thrombin from heparin-PVA. The quantity of thrombin displaced by an alpha-2-macroglobulin-free plasma fraction compared well with fibrinogen-free plasma: The eluted enzyme was largely associated with antithrombin-III. Purified antithrombin-III did not displace thrombin from heparin-PVA despite causing greater than 70% inactivation of the bound enzyme. Subsequent treatment with fibrinogen-free plasma dislodged (thrombin-antithrombin-III) at a similar rate to that of bound thrombin. We conclude that plasma contains a component(s) which displaces (thrombin-antithrombin-III) complex from immobilised heparin: presumably this leaves the heparin sites free for further use in enzyme inactivation.
 ...
PMID:Fate of thrombin and thrombin-antithrombin-III complex adsorbed to a heparinized biomaterial: analysis of the enzyme-inhibitor complexes displaced by plasma. 619 46

The ability of purified growth factors, insulin, ascorbate, and several other compounds to stimulate DNA synthesis by rabbit articular chondrocytes was studied in monolayer culture. Platelet-derived growth factor (1 U/ml), pituitary fibroblast growth factor (1-100 ng/ml), and epidermal growth factor (1-50 ng/ml) were stimulatory in a basal medium supplemented with 1% heat-inactivated fetal bovine serum. Insulin, 1-50 micrograms/ml, has small growth-promoting effects but acted synergistically with platelet-derived, pituitary fibroblast, and epidermal growth factors. Increasing concentrations of serum up to 10% enhanced the growth-promoting action of the purified factors, but not of insulin. There were indications of cooperation between insulin and bovine serum albumin and dexamethasone. Ascorbate (0.2 mM) reduced or had little growth-promoting action in the basal medium. At 5 and 10% serum concentrations, however, ascorbate promoted DNA synthesis as effectively as the purified growth factors. No significant stimulatory effect was shown by transferrin, thrombin, L-glutamine, putrescine, selenous acid, dexamethasone, 7S nerve growth factor, or multiplication-stimulating activity.
 ...
PMID:Effect of purified growth factors on rabbit articular chondrocytes in monolayer culture. I. Dna synthesis. 621 24

Reactions of heparin, covalently immobilized in hydrogel, with fibrinolysin, blood serum albumin, thrombin and fibrinogen were studied. All the proteins studied were shown to penetrate into the hydrogel pores and to interact with the immobilized heparin. Stability of the complexes was decreased in the following sequence: fibrinogen = thrombin much greater than fibrinolysin much greater than blood serum albumin. Complexes of the immobilized heparin with fibrinogen, thrombin and fibrinolysin hydrolyzed the unstabilized fibrin.
 ...
PMID:[Analysis of lytic effect on fibrin of immobilized heparin in complex with plasma proteins]. 621 39

The in vivo clearance of antithrombin III-proteinase complexes occurs via a specific and saturable pathway located on hepatocytes. We now report studies of the catabolism of antithrombin III-proteinase complexes in vitro using rat hepatocytes in primary culture. Antithrombin III-thrombin and trypsin complexes were prepared and purified to homogeneity. Ligand uptake by hepatocytes was concentration, temperature, and time dependent. Initial rate studies were performed to characterize the maximum rate of uptake, V, and apparent Michaelis constant Kapp. These studies yielded a V of 12.8 fmol/mg cell protein/min and a Kapp of 144 nM for antithrombin-trypsin complexes. Competition experiments with antithrombin III, antithrombin III-proteinase complexes, alpha 2-macroglobulin-methylamine, asialoorosomucoid and the neoglycoproteins, fucosyl-bovine serum albumin (BSA), N-acetylglucosaminyl-BSA, and mannosyl-BSA indicated that only antithrombin III-proteinase complexes were recognized by the hepatocyte receptor. Uptake studies were performed at 37 degrees C with 125I-antithrombin III-trypsin and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in conjunction with autoradiography. These studies demonstrate time-dependent uptake and degradation of the ligand to low molecular weight peptides. In addition, there was a time-dependent accumulation of a high molecular weight complex of ligand and a cellular protein. This complex disappeared when gels were performed under reducing conditions.
 ...
PMID:Hepatocyte receptors for antithrombin III-proteinase complexes. 633 Jan 34

A unique and heretofore undescribed glycoprotein with unusual properties has been purified and characterized from the culture medium of endothelial cells. This protein is synthesized constitutively by bovine, porcine, and human endothelial cells, by vascular smooth muscle cells, and by fibroblasts from dermis and ligament. It is also a biosynthetic product of some murine malignant and/or transformed cell lines but was not uniformly observed in cells derived from human neoplasms. The glycoprotein exhibited an apparent molecular weight by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of approximately 39,000 before reduction, and of approximately 43,000 (43K protein) in the presence of dithiothreitol. Amino acid analysis revealed high levels of potentially acidic residues (Asx + Glx = 303 residues/1000) and of cysteine (35 residues/1000). Limited proteolysis indicated that both disulfide bonds and mannosylated sites were distributed throughout the protein chain. Neither phosphate nor sulfate was incorporated into the 43K protein during biosynthetic labeling of endothelial cells. In addition, the 43K protein did not bind to heparin, thrombin, gelatin, or fibronectin and displayed no affinity for [3H]diisopropyl fluorophosphate. In contrast, the 43K protein demonstrated a high affinity binding to bovine serum albumin which was dissociable only by sodium dodecyl sulfate. A complete lack of identity with several prominent serum and platelet proteins and with other mesenchymal cell products was shown by one- and two-dimensional peptide mapping, affinity chromatography, and immunological studies. Immunofluorescence staining of endothelial cells showed a granular distribution for the 43K protein that was typical of a secreted protein. The function of this apparently novel glycoprotein is presently not known. Its synthesis by normal mesenchymal cells and by malignant or transformed cells of both ectodermal and endodermal origin suggests a general role in cell function that is independent of transformation.
 ...
PMID:Characterization of a novel serum albumin-binding glycoprotein secreted by endothelial cells in culture. 636 55


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>