scholarly journals Studies on the Structure and Subunit Composition of Human Antihaemophilic Factor

1977 ◽  
Author(s):  
J. J. Gorman
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Peptide Mapping ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Protein S ◽  
Molecular Forms ◽  
Major Band ◽  
Human Factor Viii ◽  
Von Willebrand

Human antihaemophilic factor has been purified by hydroxylapatite chromatography following precipitation from plasma and gel filtration on Sepharose 6B.Application to hydroxyiapatite was in 0.02 M tris HCl (pH 7.35) – 0.14 M NaCl and after washing with 5mM phosphate (pH 6.8) – 0.1 M NaCI the antihaemophilic factor was eluted with 0. 1M phosphate (pH 6.8) – 0.1M NaCl. Factor VIII coagulant activity, factor VIII related antigen and von Willebrand factor activity eluted simultaneously.The protein(s) had a molecular weight in excess of 500,000 and multiple subunits as shown by electrophoresis in 5% acrylamide gels containing sodium dodecyl sulphate;without reduction the protein failed to enter these gels but following reduction multiple bands were observed, the major band had a molecular weight around 200,000.Thin layer peptide mapping demonstrated structural inter-relationship between the 200,000 dalton protein and three of the smaller species, however, two other unrelated smaller species were evident.It is apparent from these findings that human factor VIII may exist as multiple molecular forms due to heterogeneity of one subunit (MW around 200,000) and the molecular structure may include other smaller non-identical subunits. The structure-function relationships of these subunits remains to be elucidated.

scholarly journals Immunologic studies of native and modified human factor VIII/von Willebrand factor

Blood ◽  
1979 ◽  
Vol 54 (2) ◽  
pp. 310-321 ◽  
Author(s):  
ME Switzer ◽  
PA McKee
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Proteolytic Enzymes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Procoagulant Activity ◽  
Human Factor Viii ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Factor VIII/von Willebrand factor (FVIII/vWF) is a glycoprotein with a molecular weight greater than one-million daltons. Two activities are associated with this large molecule: FVIII procoagulant activity and vWF activity. Incubation of FVIII/vWF with proteolytic enzymes causes rapid inactivation of the FVIII procoagulant activity but has little effect on the vWF activity or antigenicity. In an attempt to gain insight into the structural features required for these two activities, antisera were raised in rabbits to normal, thrombin-inactivated, and plasmin-inactivated FVIII/vWF. All of these proteolytically modified forms of FVIII/vWF cross-reacted with each of the rabbit antisera; each blocked the ability of a human inhibitor to inactivate native active FVIII/vWF. Each of the antisera was a potent inhibitor of vWF activity and inactivated vWF activity at the same titer. The antisera were much less potent inhibitors of FVIII activity than of vWF activity. Antibodies to thrombin-inactivated FVIII/vWF or normal FVIII/vWF had about the same ability to inactivate FVIII procoagulant activity. Surprisingly, those to plasmin-inactivated FVIII/vWF still retained about 50% of this inhibitory capacity. A comparison of the three types of antigens by polyacrylamide gel electrophoresis in sodium dodecyl sulfate-6 M urea demonstrated that the structure of thrombin- inactivated FVIII/vWF was indistinguishable from that of normal FVIII/vWF, while plasmin-inactivated FVII/vWF was completely cleaved to lower molecular weight fragments. Some of the reported variations in the ability of rabbit antibodies to inhibit procoagulant activity may be due to partial degradation of the starting antigen. The retention by FVIII/vWF protein of its immunologic properties even after extensive proteolytic degradation suggests that under nondenaturing conditions, the conformation of the native and degraded molecules are very similar.

scholarly journals Immunologic studies of native and modified human factor VIII/von Willebrand factor

Blood ◽  
1979 ◽  
Vol 54 (2) ◽  
pp. 310-321
Author(s):  
ME Switzer ◽  
PA McKee
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Proteolytic Enzymes ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Procoagulant Activity ◽  
Human Factor Viii ◽  
Von Willebrand ◽  
Willebrand Factor

Factor VIII/von Willebrand factor (FVIII/vWF) is a glycoprotein with a molecular weight greater than one-million daltons. Two activities are associated with this large molecule: FVIII procoagulant activity and vWF activity. Incubation of FVIII/vWF with proteolytic enzymes causes rapid inactivation of the FVIII procoagulant activity but has little effect on the vWF activity or antigenicity. In an attempt to gain insight into the structural features required for these two activities, antisera were raised in rabbits to normal, thrombin-inactivated, and plasmin-inactivated FVIII/vWF. All of these proteolytically modified forms of FVIII/vWF cross-reacted with each of the rabbit antisera; each blocked the ability of a human inhibitor to inactivate native active FVIII/vWF. Each of the antisera was a potent inhibitor of vWF activity and inactivated vWF activity at the same titer. The antisera were much less potent inhibitors of FVIII activity than of vWF activity. Antibodies to thrombin-inactivated FVIII/vWF or normal FVIII/vWF had about the same ability to inactivate FVIII procoagulant activity. Surprisingly, those to plasmin-inactivated FVIII/vWF still retained about 50% of this inhibitory capacity. A comparison of the three types of antigens by polyacrylamide gel electrophoresis in sodium dodecyl sulfate-6 M urea demonstrated that the structure of thrombin- inactivated FVIII/vWF was indistinguishable from that of normal FVIII/vWF, while plasmin-inactivated FVII/vWF was completely cleaved to lower molecular weight fragments. Some of the reported variations in the ability of rabbit antibodies to inhibit procoagulant activity may be due to partial degradation of the starting antigen. The retention by FVIII/vWF protein of its immunologic properties even after extensive proteolytic degradation suggests that under nondenaturing conditions, the conformation of the native and degraded molecules are very similar.

scholarly journals Degradation of Factor VIII-Related Protein in Factor VIII Concentrates

1977 ◽  
Author(s):  
T. Jakab ◽  
R. Pflugshaupt ◽  
M. Furlan ◽  
E.A. Beck
Keyword(s):  
Factor Viii ◽  
Sodium Dodecyl ◽  
Protein S ◽  
Relative Increase ◽  
Related Protein ◽  
Normal Plasma ◽  
Human Factor Viii ◽  
Factor Viii Concentrates ◽  
Weight Protein ◽  
Von Willebrand

Lipolytic and/or proteolytic treatment of highly purified human factor VIII results in a progressive disappearance of high-molecular weight protein as shown by electrophoresis on 3% Polyacrylamide gels in the presence of sodium dodecyl sulphate. Partial degradation of factor VIII is typically accompanied by a relative increase of factor VIII-related antigen (VIII R:AG)whereas coagulant activity (VIII:C) or von Willebrand activity (VIII R:WF) may still appear intact. VIII R:AG was measured by crossed Immunoelectrophoresis against specific heterologous antibody in agarose gels. VIII R:WF was expressed as ristocetin cofactor activity in comparison with a normal plasma pool. Assuming a VIII R:AG/ VIII R:WF ratio of 1.0 in our normal plasma, we found a similar ratio using intact purified factor VIII. This ratio increased regularly following proteolytic degradation of factor VIII concentrate by contaminating proteases or plasmin. Our findings suggest that a high VIII R:AG/VIII R:WF ratio could indicate undesirable alterations of VIII-related protein(s) during plasma fractionation.

scholarly journals Structure-Function Studies of Factor VIII/Von Willebrand Protein(s)

1977 ◽  
Author(s):  
Patrick A. McKee
Keyword(s):  
Factor Viii ◽  
Single Molecule ◽  
Gel Filtration ◽  
Protein S ◽  
Fold Increase ◽  
Procoagulant Activity ◽  
Void Volume ◽  
Pas Staining ◽  
Von Willebrand ◽  
Willebrand Factor

Factor VIII (FVIII) procoagulant activity was initially thought to be a glycoprotein with a molecular weight (MW) >1 million and composed of disulfide-1inked ~200,000 MW subunits. A protein with similar properties, except lacking procoagulant activity, is in hemophilic plasma; it was identical to normal FVIII by SDS-gel analyses, isoelectric focusing, and PAS staining. Subsequently it was shown that the FVIII glycoprotein also has von Willebrand factor (vWF) activity, suggesting that both FVIII and vWF activities might be properties of the same molecule. When the FVIII/vWF protein(s) is rechromatographed on 4% agarose and 0.25 M CaCl2, virtually all the protein and vWF activity elute in the void volume, but most of the FVIII procoagulant activity elutes much later. The extent of separation of the two activities depends on the amount of protein applied to the column. Also, exposure of the FVIII/vWF to thrombin before gel filtration strikingly accentuates separation of the two activities. The reduced SDS-gel pattern of the void volume protein peak showed the 200,000 MW subunit while that of the procoagulant peak contained several subunit bands which ranged from ~30,000–100,000 MW. Removal of sialic acid from FVIII/vWF is associated with reduced ristocetin induced platelet aggregation and causes a 50-fold increase in the rate of clearance of protein from the circulation by the hepatocyte. Currently, our data suggest that FVIII procoagulant and vWF activities are properties of a single molecule composed of disulfide-bound identical subunits. Cleavage by thrombin then results in FVIII procoagulant activity. Additional cleavages, to which the molecule appears very sensitive, results in FVIII inactivation. The vWF activity is very stable—even to proteolysis—and it appears to be a function of the carbohydrate side chains of the molecule.

scholarly journals Studies of the human factor VIII/von Willebrand's factor protein. II. Identification and characterization of the von Willebrand protein

Blood ◽  
1975 ◽  
Vol 46 (3) ◽  
pp. 417-430
Author(s):  
HR Gralnick ◽  
BS Coller
Keyword(s):  
Factor Viii ◽  
Human Factor ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Related Protein ◽  
Human Factor Viii ◽  
Von Willebrand’S Factor ◽  
Von Willebrand ◽  
Identification And Characterization

The purified factor VIII-related protein we have previously characterized from normal cryoprecipitate possesses both procoagulant activity and vWf activity. We have attempted to isolate and characterize this protein from three patients with severe vWd. This protein is absent or markedly diminished in amount in these vWd patients, as judged by gel filtration, polyacrylamide-gel electrophoresis, and immunoprecipitation assays. Likewise, the procoagulant and vWf activities are deficient. As vWf activity is one of the major biologic functions of either the normal or hemophilic factor VIII-related protein, the purified protein should be designated the f VIII/vWf protein.

Affinity Chromatography of Human Factor VIII Using Human and Rabbit Antibodies to Factor VIII

1979 ◽  
Vol 42 (04) ◽  
pp. 1306-1315 ◽  
Author(s):  
Janet L Lane ◽  
H Ekert ◽  
A Vafiadis
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Affinity Chromatography ◽  
Protein Concentration ◽  
Gel Filtration ◽  
Subunit Structure ◽  
Molecular Weights ◽  
Human Factor Viii ◽  
Sds Page ◽  
Normal Human

SummaryFactor VIII, purified by gel filtration on Sepharose 2B, has an 8 band multiple subunit structure, with molecular weights ranging from 30,000 to 230,000, on reduction and SDS-PAGE at a protein concentration of 400 μg/gel. Affinity chromatography of this factor VIII preparation with insolubilized haemophilic antibody to factor VIII showed that 45-81% VIII:C and 0-33% VIILRag were attached to the column. Elution of the column with 0.25 M CaCl2 did not show VIII:C or VIILRag in the eluate. NH4SCN dissociation of the column, followed by reduction and SDS-PAGE of the dissociated protein, showed that 95 % of the protein bound by haemophilic antibody had a molecular weight similar to the low molecular weight subunits of the reduced factor VIII.In control experiments with normal Human IgG, 3% of VIII:C and 5% of VIILRag were attached to the column. NH4SCN dissociation of the column, followed by reduction and SDS-PAGE of the protein, showed 2 faint bands with molecular weight consistent with heavy and light chains of IgG.Similar experiments with antibody to factor VIII showed that 67-83% of VIILC and 61-76% of VIII:Rag were attached to the column. Elution of the column with 0.25 M CaCl2 showed 10% of the applied VIII:C, but no VIII:Rag in the eluate. NH4SCN dissociation of the column, followed by reduction and SDS-PAGE of the dissociated protein, showed an 8 band subunit structure similar to the reduced factor VIII.

Purification of Ristocetin Willebrand Factor (RWF)

1975 ◽  
Author(s):  
J. D. Olson ◽  
D. N. Fass ◽  
W. J. Brockway ◽  
E. J. W. Bowie ◽  
K. G. Mann
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Apparent Molecular Weight ◽  
Amino Sugar ◽  
Procoagulant Activity ◽  
Factor Viii Inhibitor ◽  
Induced Aggregation

A component required for the ristocetin-induced aggregation of platelets was isolated in yields of 20-30% from pooled human and porcine plasma by cryoethanol concentration of the RWF, after removal of the vitamin K dependent coagulation factors on barium citrate. The concentrate was further purified using gel filtration (4% agarose) and ion exchange (DEAE-cellulose) chromatography. Sodium dodecyl sulfate polyacrylamide gels of the isolated factor indicated an apparent molecular weight of greater than 500,000. After reduction of RWF with mercaptoethanol, a single band is resolved with an apparent molecular weight of 230,000. The purified component had no factor VIII procoagulant activity and did not compete for the activity of naturally occurring factor VIII inhibitor (human). Antisera raised in rabbits directed against the purified component inhibited the RWF activity but not the factor VIII procoagulant activity of plasma. Amino acid analysis indicated the presence of all normal amino acids and failed to detect any amino sugar. Analysis of lipid revealed a significant amount of lipid composed of mono, di and triglycerides, cholesterol, cholesterol esters and free fatty acid, with small portions of phospholipids.

scholarly journals Apparent molecular weight of purified human factor VIII procoagulant protein compared with purified and plasma factor VIII procoagulant protein antigen

Blood ◽  
1983 ◽  
Vol 62 (5) ◽  
pp. 1114-1117 ◽  
Author(s):  
MJ Weinstein ◽  
CA Fulcher ◽  
LE Chute ◽  
TS Zimmerman
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Apparent Molecular Weight ◽  
Discontinuous System ◽  
Major Band ◽  
Molecular Weights ◽  
Human Factor Viii ◽  
Plasma Factor ◽  
Factor Viii Concentrates ◽  
Electrophoretic Techniques

Abstract We have compared apparent molecular weights of purified factor VIII procoagulant protein (VIII:C) and VIII:C antigen (VIII:CAg) by two different NaDodSO4 gel electrophoretic techniques. In a discontinuous NaDodSO4–7.5% polyacrylamide system, reduced and unreduced VIII:C, purified from commercial factor VIII concentrates by a monoclonal antibody immunoadsorption technique, showed a major doublet at mol wt 0.79 and 0.8 X 10(5) and less intense bands extending up to 1.9 X 10(5). In NaDodSO4–4% polyacrylamide/0.5% agarose gels (NaDodSO4–4% PAAGE), purified VIII:C had a major band of mol wt 1.0 X 10(5), with minor bands of mol wt 0.96, 1.1, 1.4, 1.6, 1.8, 2.2, and 2.4 X 10(5). In NaDodSO4–4% PAAGE of 125I-anti-VIII:C-Fab-VIII:CAg complexes, the major and minor forms of VIII:CAg in purified VIII:C had the same molecular weight as above when calculated by subtracting the molecular weight of 125I-Fab from 125I-Fab-VIII:CAg. In both plasma and factor VIII concentrate, a band of mol wt 2.4 X 10(5) predominated, and minor VIII:CAg forms of mol wt 2.6, 1.8, 1.2 and 1.0 X 10(5) were also visible. We conclude that the molecular weight of plasma VIII:CAg forms agree with those derived from protein stains of purified VIII:C in the NaDodSO4–4% PAAGE system, but that consistently lower molecular weight values are obtained for purified VIII:C in the discontinuous system. Both native and either disaggregated or proteolyzed VIII:C species are present in the purified VIII:C preparation.

Pregnancy-Induced Thrombocytopenia in Pseudo-Von Willebrand Disease

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4658-4658
Author(s):  
Simi George ◽  
Laura L. Donahue ◽  
Dorothy M (Adcock) Funk ◽  
Steven L. Allen
Keyword(s):  
Molecular Weight ◽  
Platelet Count ◽  
Factor Viii ◽  
High Molecular Weight ◽  
Conflicts Of Interest ◽  
Post Partum ◽  
Von Willebrand Disease ◽  
Human Factor Viii ◽  
Platelet Disorder ◽  
Von Willebrand

Abstract Abstract 4658 Platelet-type von Willebrand disease, or pseudo-VWD, is a rare congenital platelet disorder due to a mutation in the glycoprotein 1b alpha receptor. This results in increased binding of normal VWF to platelets, leading to platelet aggregation and intermittent thrombocytopenia. Although the mechanism is similar to type IIb VWD, this gain of function mutation affects the platelet, rather than plasma VWF. We report a patient with pseudo-VWD who developed progressive thrombocytopenia during pregnancy. She was initially seen at 10 weeks gestation, when the platelet count was 143 × 109 /L (figure 1). As the pregnancy progressed, the platelet count decreased, accompanied by an inverse rise in VWF antigen and activity, factor VIII activity, and an increase in high molecular weight (HMW) multimers (figure 2). The VWF activity to antigen ratio remained abnormal at all times. At the time of delivery, the platelet count reached a nadir of 36 × 109/L. Post-partum, the platelet count normalized to 185 × 109/L with a concomitant fall in VWF antigen and activity levels. VWF multimer analysis after delivery showed an absence of high molecular weight multimers.FIGURE 1FIGURE 1. FIGURE 2Weeks GestationPlatelet count (×109 /L)VWF antigenVWF activityFactor VIIIPlatelet aggregationVWF multimers1014381%35%88%↑ ristocetin 0.6normal3654144%57%205%not donenormal+15 post-partum18555%19%49%not doneHMW multimers absent The likely etiology of the progressive decrease in the platelet count is secondary to the physiologically stimulated rise in VWF levels during pregnancy. With rising VWF levels, the abnormal platelet GP1b alpha receptor binds VWF, resulting in platelet-VWF aggregates with subsequent clearance. Transfusion of normal platelets would be the only way to correct the abnormality. Our patient, a Jehovah's Witness, would not accept platelet transfusion if it became necessary. She underwent an uncomplicated cesarean section for obstetric indications. Our patient's family was the subject of the landmark article initially describing this condition (Weiss HJ, Meyer D, Rabinowitz R, et al. Pseudo- von Willebrand's disease: An intrinsic platelet defect with aggregation by unmodified human factor VIII/von Willebrand factor and enhanced adsorption of its high-molecular-weight multimers. N Engl J Med 1982; 306:326-333). This patient is the 2-year old who was not tested when the family was initially evaluated. To our knowledge, this is the first reported case of pregnancy-associated thrombocytopenia in a patient with pseudo-VWD. Disclosures: No relevant conflicts of interest to declare.

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

1981 ◽  
Vol 45 (03) ◽  
pp. 242-246 ◽  
Author(s):  
Miha Furlan ◽  
Beat A Perret ◽  
Eugene A Beck
Keyword(s):  
Molecular Weight ◽  
Factor Viii ◽  
Human Factor ◽  
Low Molecular Weight ◽  
Human Factor Viii ◽  
Large Factor ◽  
Cofactor Activity ◽  
Von Willebrand ◽  
Ristocetin Cofactor ◽  
Ristocetin Cofactor Activity

SummaryHuman factor VIII/von Willebrand protein is a population of multimers which vary in size but contain apparently identical subunits. Large-molecular-weight forms possess higher ristocetin cofactor/von Willebrand activity than the native smaller oligomers. Disulfide reduction of large factor VIII multimers results in progressively decreasing molecular size and a loss of ristocetin cofactor activity. Small molecular forms of factor VIII were adsorbed onto gold granules (average diameter 20-30 nm) and thereby increased their ristocetin cofactor activity. The amount of adsorbed material and the extent of activation were dependent on the pH of the colloid suspension. The maximum recovery of von Willebrand activity was observed at pH 4.75. Aggregation of fixed human platelets by factor VIII-coated gold particles was dependent on ristocetin concentration and was not competitively inhibited by unbound low-molecular-weight factor VIII. These results suggest that the subunits of the native small factor VIII species possess potential binding affinity for platelet receptors, which is manifested following formation of large factor VIII polymers. We conclude that an optimal size of remarkably high molecular weight is required for efficient aggregation of platelets by factor VIII as occurs during the primary phase of hemostasis.

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