Von Willebrand Activity of Low Molecular Weight Human Factor VIII Increases by Binding to Gold Granules

Furlan, Miha; Perret, Beat A.; Beck, Eugene A.

doi:10.1055/s-0038-1650179

Cited by 15 publications

(4 citation statements)

References 10 publications

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“…It has been shown by gel filtration of cryoprecipitate on large-pore agarose that the large multimers eluting in the void volume have a considerably higher ristocetin cofactor activity per unit antigen than the later-eluting vWF species of smaller size [28]. Gentle disulfide reduction of large vWF multimers resulted in decreasing molecular size and loss of ristocetin cofactor activity; small molecular forms of vWF were adsorbed onto colloidal gold granules and thereby increased their platelet-agglutinating activity [29]. vWF multimers of different sizes were fractionated by gel filtration and the resulting fractions subjected to binding studies in the presence of ristocetin (vWF binding to GPIb) or after addition of thrombin (vWF binding to the complex GPIIb/IIIa).…”

Section: Introductionmentioning

confidence: 99%

Von Willebrand factor: molecular size and functional activity

Furlan

1996

Annals of Hematology

210

176

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Von Willebrand factor (vWF) is the largest protein found in plasma. It circulates in blood as a series of multimers ranging in size from 500 to 20,000 kDa. The variable molecular weight of vWF is due to differences in the number of subunits comprising the protein. vWF mediates platelet adhesion to subendothelium of the damaged blood vessel. Only the largest multimers are hemostatically active. Each vWF subunit contains binding sites for collagen and for platelet glycoproteins GPIb and GPIIb/IIIa. Multiple interactions of repeating binding sites in vWF multimers with adhesive protein(s) of the subendothelium and with receptors on the platelet surface lead to "irreversible" binding of platelets to the exposed subendothelium. Functional properties of vWF are typical of multisubunit proteins encoded by autosomal loci. The phenotype of von Willebrand disease is determined by the properties of the dysfunctional subunits which become incorporated into heteropolymeric forms of vWF. Absence of large vWF multimers, seen in type 2A von Willebrand disease and in myeloproliferative disorders, is associated with bleeding tendency. On the other hand, in patients with vWF multimers of supranormal size, as they occur in thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), there is an increased risk of thrombosis. Proteolytic enzyme(s) are involved in physiologic regulation of the polymeric size of vWF. We have purified from human plasma a protease cleaving vWF at the same peptide bond that is also cleaved in vivo. vWF was quite resistant against the protease in a physiologic buffer but was degraded at low salt concentration or in the presence of 1 M urea. It appears that a conformational change in the vWF molecule exposes the specific protease-sensitive peptide bond and thus enhances degradation of vWF multimers. In some variants of type 2A vWF, the cleavage site in the vWF subunit is more susceptible to proteolytic degradation than in normal vWF, whereas in patients with TTP or HUS the protease activity may be suppressed. vWF-degrading protease plays an important role in pathogenesis of congenital or acquired disorders of hemostasis and thrombosis.

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Section: Introductionmentioning

confidence: 99%

Von Willebrand factor: molecular size and functional activity

Furlan

1996

Annals of Hematology

210

176

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“…It has tentatively been suggested that the results of the latex antigen assay may correspond more closely to the functional activity of FVIII/vWF than those of the EIA (4). reduced with 10 mM Z-mercaptoethanol at 37" C as described elsewhere (5). At different time-intervals, aliquots were withdrawn from the incubation mixture and alkylated with iodoacetamide at 25 mM final concentration.…”

Section: Lntroductionmentioning

confidence: 99%

Reactivity of Small Molecular Forms of Human Factor VIII/von Willebrand Factor with Botrocetin and Anti-Factor VIII-Coated Latex Particles

1985

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SummaryTwo recently developed tests for measurement of factor VIII/von Willebrand factor (FVIII/vWF), i.e. platetelet agglutination by botrocetin and a kinetic latex antigen assay, were compared with ristocetin cofactor and electroimmunoassay, in respect with FVIII/vWF size-distribution. FVIII/vWF was measured in six cases of atypical von Willebrand’s disease (type II), in gel-filtered fractions of normal cryoprecipitate and in the course of depolymerization of purified normal FVIII/vWF by disulfide reduction. Small molecular forms of FVIII/vWF from normal and variant type II plasma, and those derived by disulfide reduction of high-molecular weight FVIII/vWF, showed remarkably decreased reactivity in ristocetin-, botrocetin- and latex-assay. We conclude that for botrocetin-induced platelet agglutination, as well as for agglutination of antibody-coated latex particles, multiple interactions with repeating subunits of FVIII/vWF are required. As a practical consequence, the combined measurement of FVIII/vWF by the latex test and electroimmunoassay provides a simple tool for discriminating between the classical von Willebrand’s disease and its variants.

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“…Marker bars equal 0.1, 0.1, and 0.03 pm, in A, B, and C, respectively. platelet surface receptors ( 102) and the optimal multimer size of the Factor VIII for expression of platelet aggregation effects (103).…”

Section: Receptor Applicationsmentioning

confidence: 99%

Colloidal Gold: A Pluripotent Receptor Probe

Handley

Chien

1983

Experimental Biology and Medicine

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Colloidal gold is an electron-dense, lyophobic colloid that readily forms a stable electrostatic interaction with a variety of macromolecules. Monodispersed colloids ranging from 3-150 nm in diameter can be produced to provide the researcher with flexibility in selecting the optimally sized probe. Gold labeling of antibodies and lectins has been extensively used to study surface antigens and cell components. Recently, the use of gold labeling has been extended to study receptor-ligand binding, enzyme-substrate reactions, and transcellular pathways. Published applications include gold labeling of metabolites (low-density lipoproteins), enzymes (DNAase and RNAase, RNA polymerase, thrombin, collagenase, elastase), hormones (insulin, epidermal growth factor, glucagon), circulating plasma proteins (asialoglycoprotein, a2-macroglobulin, factor VIII-von Willebrand factor), and endotoxins (tetanus toxin, cholera toxin). This broad spectrum of applications emphasizes the versatility and usefulness of colloidal gold as a probe in areas of cell biology related to receptors, endocytosis, transport, and functions of proteins.

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Von Willebrand Activity of Low Molecular Weight Human Factor VIII Increases by Binding to Gold Granules

Cited by 15 publications

References 10 publications

Von Willebrand factor: molecular size and functional activity

Von Willebrand factor: molecular size and functional activity

Reactivity of Small Molecular Forms of Human Factor VIII/von Willebrand Factor with Botrocetin and Anti-Factor VIII-Coated Latex Particles

Colloidal Gold: A Pluripotent Receptor Probe

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