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

---

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

The reactivity of fibrinogen crosslinking sites with thrombin-free, preactivated factor XIII (F. XIIIa) was investigated under different conditions such as increased ionic strength, presence of urea, protamine sulfate (PS) or of varying concentrations of monodansylcadaverine (MDC). Crosslinking and incorporation of MDC into fibrinogen or fibrin gamma- and alpha-chains were evaluated by SDS-polyacrylamide gel electrophoresis. According to our results, rates of crosslinking of, and of MDC incorporation into, both gamma- and alpha-chains of fibrinogen were low under physiological conditions; they were not significantly influenced by the presence of either 1.0 M NaCl or 1.0 M urea. In contrast, 0.01% PS precipitated fibrinogen, and, simultaneously, significantly increased the rates of crosslinking and of MDC incorporation into both gamma- and alpha-chains. MDC, at concentrations above approximately 6 mM, also precipitated fibrinogen, and, up to a concentration of about 9 mM, markedly enhanced the reactivity of acceptor crosslinking sites. Our results suggest that solubility of fibrinogen and the conformational arrangement of its subunit chains are closely interdependent; the reactivity of crosslinking sites with F. XIIIa seems to be a function of this conformational state.
...
PMID:Reactivity of fibrinogen crosslinking sites in the absence of thrombin. 1 Jun 37

1. The influence of the pH on the separation of high molecular weight derivatives obtained by a limited action of thrombin on fibrinogen was studied by agarose gel chromatography. When the pH of the elution buffer was 8.5, non crosslinked associations were easily separated in two peaks eluted prior to the fibrinogen peak: one contained a dimer, the other several high polymers. At pH 6.5, only the fibrinogen peak appeared: the fibrinogen molecule proteolysed by thrombin formed no stable associations at this pH and was eluted with the intact fibrinogen molecule. In the presence of factor XIII and Ca++, numerous associations were obtained which are independant of the pH. 2. The polypeptide chain composition of the different species separated at pH 8.5 was studied by SDS-polyacrylamide gel electrophoresis. This technic showed Aalpha, Bbeta and gamma chains in the fibrinogen peak, whereas in the chromatographic fractions containing the dimer four bands corresponding to Aalpha, alpha, Bbeta and gamma chains were found. In the peak containing the high polymers, only the presence of alpha, Bbeta and gamma chains was demonstrated. 3. These experimental results concerning the effect of pH on the formation of soluble complexes showed that the presence of fibrin monomers in fibrinogen solution was not sufficient to promote any associations. The formation of such derivatives is strongly dependent on the pH of the solution. This obviously can be explained by an influence of the pH either on the ionization of polymerisation sites and the intermolecular bonds between the complex units or on the unmasking of the polymerisation sites by a hypothetical pH induced conformational change of the fibrinogen molecule.
...
PMID:Soluble fibrin complexes: separation as a function of pH and characterization. 1 16

Pure alpha2M is prepared with fresh plasma as starting material, to prevent the interaction of alpha2M from proteolytic enzymes of plasma such as thrombin, plasmin and kallikrein. During the purification steps, polybrene and aprotin are used as inhibitors and plasminogen is absorbed onto bentonite. When alpha 2M is submitted to polyacrylamide gel electrophoresis (PAA) containing 0.1% SDS, a complete dissociation in two half-molecules of MW 380,000 occurs. When alpha2M is incubated in 1% SDS and 1% beta-mercaptoethanol as reducing agent, only one component of MW 190,000 is observed in PAA-SDS. This experiments show that the alpha2M molecule consist of two symetric halves of same MW (380,000) linked by non covalent bonds. Each two-half-molecules is made of two polypeptides chains MW 190,000 linked by disulfide bonds. Thus alpha2M molecule contains four polypeptides chains having a same MW. The same techniques were applied to the study of alaph2M proteinases complexes. Three different proteinases (plasmin, trypsin and papain) were used in these experiments. Trypsin and papain are commercialy available. Plasminogen was obtained by affinity chromatography and activated into plasmin by insoluble streptokinase fixed on PAB cellulose.
...
PMID:[Studies on human alpha-2 macroglobulin structure and its complexes with proteases, using polyacrylamide gel electrophoresis]. 5 41

Analysis of platelet membrane proteins and glycoproteins by SDS polyacrylamide gel electrophoresis was carried out before and after treatment with thrombin. Extended incubation with thrombin (in the presence of EDTA or adenosine, which inhibit aggregation) produced extensive changes in the bands observed. With incubation times of a few minutes however, the changes were restricted to a glycopeptide, GP IV (approx. 90,000 Daltons) and one or two polypeptides of low molecular weight, in particular polypeptide 16 (approx. 23,000 Daltons). At 0--3 degrees C only polypeptide 16 was still hydrolyzed. Chymotrypsin, which does not activate platelets, attacked glycopeptides I, II, III but no changes were apparent in GP IV and polypeptide 16. When chymotrypsin-treated platelets were further incubated with thrombin, only GP IV and one to two low molecular weight polypeptides, especially polypeptide 16, were affected. As polypeptide 16 appears to be an integral membrane component it is possible that it, either by itself or in combination with GP IV, represents the primary thrombin substrate involved in platelet activation. Aggregated IgG, which also activates platelets, does not modify the membrane glycoproteins but does change the low molecular weight region in particular band 16.
...
PMID:Effects of thrombin, chymotrypsin and aggregated gamma-globulins on the proteins of the human platelet membrane. 7 80

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

The effect of intravenous infusions of purified homologous FDP and thrombin on fibrinogen synthesis was evaluated in rabbits. De novo fibrinogen production was measured by the rate of incorporation of 75SeM into circulating fibrinogen. After receiving either 100 or 200 NIH U/kg purified homologous thrombin over 1 hr, rabbits demonstrated threefold and fivefold increases in fibrinogen synthesis, respectively. A correlation between the titers of FDP-fdp and the degree of fibrinogen synthesis was evident. Prior administration of epsilon-ACA prevented the accelerated synthesis of fibrinogen induced by thrombin and inhibited the appearance of FDP-fdp in serum. epsilon-ACA did not interfere with normal fibrinogen production. Fibrinogen synthesis was assessed following infusions of FDP prepared by vitro by digestion of rabbit fibrinogen with plasmin and subsequently identified on SDS-polyacrylamide gels. Preparations which contained predominantly stage 2 intermediate (X, Y, D, and E) or stage 3 final (D and E) fragments accelerated fibrinogen synthesis, whereas those containing predominantly stage 1 fragment X did not. Prior treatment with epsilon-ACA did not alter these results. Infusion of the supernatants derived from immunoprecipitation of the FDP by either anti-rabbit fibrinogen antibody or specific anti-human D and E antibodies significantly diminished the enhanced fibrinogen synthesis induced by the unadsorbed materials. These experiments suggest that the accelerated fibrinogen synthesis induced by thrombin is mediated by FDP, with fragments D and E appearing to be the most potent.
...
PMID:The effect of homologous thrombin and fibrinogen degradation products on fibrinogen synthesis in rabbits. 21 23

Platelets from a patient with eosinophilic leukaemia were not aggregated by ristocetin. The defect was not corrected by normal human plasma and was due to a platelet abnormality. The patient's platelets also showed a diminished sensitivity to aggregation by bovine factor VIIIVWF. The defect was not associated with a prolonged bleeding time. No abnormalities were detected in ADP, collagen or thrombin-induced platelet aggregation. Biochemical studies showed that the platelets were deficient in sialic acid. This deficiency was associated with a reduced staining for glycoprotein I following SDS-polyacrylamide gel electrophoresis. The results suggest an acquired platelet surface abnormality.
...
PMID:A platelet defect in a patient with eosinophilic leukaemia: absent ristocetin-induced platelet aggregation associated with a reduced platelet sialic acid content. 45 58

Plasma and serum of humans or experimental animals contain a factor which destabilizes F-actin. The factor has no DNAse or thrombin activity and after incubation with F-actin does not modify the position of the actin band on a SDS polyacrylamide gel. Hence it probably depolymerizes F-actin.
...
PMID:An actin-destabilizing factor is present in human plasma. 47 68

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.
...
PMID:Isolation and characterization of granulocyte lysosomal proteins and study of their effects on the clotting system. 54 40

Human platelet plasma membrane glycoprotein I with an apparent molecular weight of approximately 150,000 has been shown to be one of the proteins retained by thrombin immobilized on Sepharose 4B. The retained glycoprotein has been recovered by sodium dodecyl sulfate elution and characterized by SDS polyacrylamide gel electrophoresis in the presence of 2-mercaptoethanol.
...
PMID:Affinity chromatographic demonstration of a thrombin binding protein from the platelet plasma membrane. 69 35


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

---