Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: DrugBank:APRD00631 (Gel)
 14,881 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

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

Antiplasmin activity was shown to be released from washed pig platelets by thrombin following a time course similar to that of 3H-serotonin. Antiheparin activity (platelet factor 4) appeared to be released by thrombin at a slower rate than 3H-serotonin or antiplasmin activity. Subcellular fractionation of pig platelets showed that the storage site for antiplasmin is probably the dense (amine storage) granules. Antiheparin was distributed among all of the subcellular particulate fractions except the fraction rich in dense granules. Material released from washed pig platelets and concentrated by ZnSO4 precipitation (crude antiheparin) was found to be rich in antiplasmin activity. Gel filtration on Sephadex G-150, DEAE cellulose column chromatography, and polyacrylamide gel electrophoresis showed that pig platelet antiplasmin is a low molecular weight (approximately 30,000 d) material of alpha1-globulin electrophoretic mobility. It was found to be heat labile and also inhibitory to the caseinolytic activity of trypsin but had no effect on the action of thrombin on fibrinogen. These data indicate that platelet antiplasmin is distinct from platelet antiheparin.
 ...
PMID:Platelet antiplasmin: its extrusion during the release reaction, subcellular localization, characterization, and relationship to antiheparin in pig platelets. 13 45

Solutions of plasminogen-free human fibrinogen alone or (1) treated with sodium p-chloromercuribenzoate in order to inactivate factor XIII, or (2) enriched with factor XIII, cysteine and CaC12, were clotted with plasmin-free human thrombin and incubated under sterile conditions. The clots dissolved gradually within 2 days (fibrin from sodium p-chloromercuribenzoate-treated fibrinogen) to 15 days (fibrin from factor XIII-enriched fibrinogen). This proteolytic process was not affected by soybean trypsin inhibitor but was completely inhibited by hirudin. Gel electrophoresis of the thrombin digests indicated the formation of bands equivalent to bands X, Y, D and E of plasmin digests of fibrinogen. The two latter bands, whose identity was confirmed by immunoelectrophoresis, appeared at a more advanced stage of proteolysis than the corresponding bands of plasmin digests. The number of isopeptide bonds present did not appear to affect the rate of release of acid-soluble peptides. Gel electrophoresis and the rate of release of acid-soluble peptides indicated that fewer bonds are hydrolysed by thrombin at the time of the complete solubilization of the clot than are split by plasmin when fibrinogen becomes unclottable by thrombin.
 ...
PMID:Fibrin digestion by thrombin. Comparison with plasmin-digested fibrinogen. 13 48

The cyanogen bromide fragment, N-DSK, containing the NH2-terminal portions of the three chains of fibrinogen, was found to exist in dimeric and polymeric forms. These different forms gave rise to identical chain fragments on reduction and alkylation. The B beta chain of N-DSK from fibrinogen and the beta chain of N-DSK from fibrin were isolated and characterized. The B beta chain fragment has a blocked NH2-terminal residue, and fibrinopeptide B is released on digestion with thrombin. The beta chain fragment has glycine as NH2-terminal residue. The molecular weight of the B beta chain fragment is 12200 as determined by ultracentrifugal analysis. Gel electrophoresis in sodium dodecyl sulphate gave the molecular weights of 14000 and 13000 for the B beta chain and beta chain fragments, respectively. The NH2-terminal B beta chain fragment consists of 118 amino acid residues and the beta chain fragment of 104 residues. The amino acid sequence of beta chain fragment is identical to B beta chain fragment except for the fibrinopeptide B portion. The isolation of a B beta-related fragment (B beta +), with a molecular weight of 30000, is also reported. The presence of B beta + was explained on the basis of incomplete cleavage at the Met-118 residue during treatment with cyanogen bromide. Some functional aspects of the B beta chain fragment are discussed.
 ...
PMID:Primary structure of human fibrinogen and fibrin. Structural studies on NH2-terminal part of B beta chain. 15 26

Washed human platelets were solubilized and the proteins were separated by preparative gel electrophoresis in the presence of sodium dodecyl sulphate. The gel was cut into slices and the effect of the eluted proteins on the clotting of fibrinogen by thrombin was evaluated. The isolate from only one gel slice strongly inhibited the clotting of fibrinogen. The prolongation of the clotting time was dependent on the concentration of the protein and reached a plateau around 5 microgram. Gel electrophoresis of this isolate showed a prominent glycoprotein with an apparent Mr=150 000. Gel filtration studies with [125I]thrombin showed that the protein isolate bound a significant amount of thrombin which could be displaced with unlabelled thrombin. Another preparation from the same gel or purified gamma-globulin did not bind thrombin or prolong the clotting time of fibrinogen. Glycoprotein I was isolated from human platelets by affinity chromatography on lectin-Sepharose columns. The isolated glycoprotein prolonged the clotting of fibrinogen and bound [125I]thrombin which could be displaced by unlabelled thrombin. It is proposed that the high affinity receptor of thrombin on human platelets is glycoprotein I. In addition, the antithrombin activity of intact platelets is due to binding of thrombin to this glycoprotein.
 ...
PMID:Thrombin receptors of human platelets: thrombin binding and antithrombin properties of glycoprotein I. 46 56

In this study we have explored the interaction of thrombin with platelets from human and rat. Compared to human platelets, rat platelets suspended in plasma required a higher concentration of thrombin for aggregation. This difference in sensitivity to thrombin was maintained when platelets were washed and suspended in buffer. Platelets from both mammals bound thrombin and showed a similar number of binding sites. However, the apparent dissociation constant of thrombin binding for rat platelets was approximately 15-fold higher than that for human. Thus, the decreased aggregation response of rat platelets may be due to a reduced binding of thrombin to its receptor. It is known that the thrombin receptor is located on the platelet surface. Gel electrophoresis of platelets followed by specific staining as well as fluorography showed significant differences in the surface glycoproteins of human and rat platelets. Human platelets showed labeled components corresponding to 210,000 and 160,000 daltons, whereas rat platelets showed glycoproteins with molecular weights of 240,000 and 190,000. A 135,000-dalton component was present in platelets from both sources. These results suggest that either or both glycoproteins of 210,000 and 160,000 daltons may be involved in the interaction of thrombin with human platelets.
 ...
PMID:Interaction of thrombin with mammalian platelets. 47 73

Bleeding times of mink with the Chediak-Higashi (CH) syndrome was markedly prolonged. Platelet counts were normal but there was an impaired platelet aggregation response to collagen. The metabolic adenine nucleotide pool of platelets from normal and CH mink was labeled with 14C-adenine and the platelets were gel-filtered. Gel-filtered platelets (GFP) from CH mink contained only 37.9% of the adenosine triphosphate (ATP) and 9.6% of the adenosine diphosphate (ADP) found in normal platelets and the ATP/ADP ratio was similar to the 14C-ATP/14C-ADP ratio. Platelet content of Ca2+, Mg2+, and in particular 5-hydroxytryptamine was decreased. When GFP were incubated with thrombin to induce maximal secretion, only negligible amounts of ATP and ADP were released. The specific activity of the extracellular nucleotides approximated that within the platelet. These findings suggest that the stored nucleotide pool in CH platelets is virtually absent and that the abnormalities in platelet function may be due, in part, to the essential absence of secretable ADP and serotonin. The release of Ca2+ and Mg2+ by CH platelets was 56% and 27.8% of normal, respectively.
 ...
PMID:Characterization of platelets from normal mink and mink with the Chediak-Higashi syndrome. 53 91

Bovine thrombin was insolubilized by attachment to cyanogen bromide-activated Sepharose (Sepharose-thrombin) or to activated (Affi-Gel 10) agarose containing a 10 A long arm (Affi-Gel-thrombin). Coupling in both instances approximated 7,000 units of thrombin per ml packed gel as determined by 125I-thrombin incorporation. The thrombin beads hydrolyzed the synthetic tripeptide Bz-Phe-Val-Arg-pNA (S-2160) at different rates, with the Sepharose-thrombin more active (220 esterase units per ml) than Affi-Gel thrombin (20.4 units per ml). The Km was significantly higher for the insolubilized thrombins (2 X 10(-3) M) than uncoupled thrombin (Km = 8 X 10(-5) M). The Sepharose-thrombin activated factor VIII significantly more rapidly than Affi-Gel-thrombin. Neither matrix-bound thrombin clotted a fibrinogen solution or liberated significant amounts of fibrinopeptides over 48 hr. This data indicates that a proteolysis of factor VIII, rather than a complex with thrombin, is the method of activation of factor VIII and that factor VIII is more accessible to the action of immobilized thrombin than is fibrinogen.
 ...
PMID:The action of immobilized thrombin on factor VIII, fibrinogen and a synthetic tripeptide. 56 72

The action of ancrod on fibrinogen and prothrombin metabolism was studied in six healthy individuals by the use of 131I-fibrinogen and 125I-prothrombin and by measurement of blood levels of fibrinopeptide A. Two untreated healthy controls were studied at the same time. Rapid defibrinogenation occurred during the initial 3 hr ancrod infusion, and fibrinogen levels were maintained near zero throughout the study. Large quantities of non-thrombin-clottable TCA-precipitable 131I material could be demonstrated in the circulation, reaching a maximum 3 to 6 hr after ancrod infusion and clearing with a half-life of 6 hr. Gel filtration of 6 hr plasmas demonstrated the presence of complexes larger than fibrinogen, as well as degradation products of fibrinogen-fibrin. Prothrombin concentration and metabolism were unchanged by ancrod treatment. Fibrinopeptide A levels in the ancrod group were greather than 4,000 ng/ml during the initial defibrinogenation, declined to greater than 80 ng/ml, and then increased to high levels after 3 days. These studies provide explanations of previous observations concerning the specificity of ancrod and demonstrate that rapid clotting of fibrinogen and dissolution of fibrin can occur in vivo without recruitment of the classic coagulation mechanism.
 ...
PMID:The effects of ancrod, the coagulating enzyme from the venom of Malayan pit viper (A. rhodostoma) on prothrombin and fibrinogen metabolism and fibrinopeptide A release in man. 64 85

The complexes formed by antithrombin III with activated bovine Factor X and thrombin have been studied by gel electrophoresis in dodecyl sulfate. When subjected to electrophoresis at pH 7, the complexes remain intact, whereas electrophoresis at pH 9 in the presence of Tris results in their dissociation. Dissociation of both the Factor Xa-antithrombin III complex and the thrombin-antithrombin III complex in dodecyl sulfate produces a modified form of antithrombin III which, unlike the native inhibitor, apparently consists of two chains. Gel electrophoresis of the dissociated complexes has also been used to study the sites where the complexes are cleaved by the respective enzymes. The cleavage of the Factor Xa-inhibitor complex by Factor Xa apparently results from hydrolysis of a single bond in the enzyme part of the complex and releases a 15,000-dalton NH2-terminal fragment of the heavy chain, with the light chain attached. Cleavage of the thrombin-inhibitor complex by thrombin involves several cleavages of the heavy (B) chain of the thrombin part of that complex. Neither enzyme-inhibitor complex is subject to cleavage by free enzyme in the inhibitor part of the complex under the conditions used.
 ...
PMID:Dissociation of complexes and their derivatives formed during inhibition of bovine thrombin and activated factor X by antithrombin III. 76 13


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