Evidence for a Discrete Binding Protein of Plasminogen Activator Inhibitor in Plasma

1988 ◽  
Vol 59 (03) ◽  
pp. 392-395 ◽  
Author(s):  
Björn Wiman ◽  
Tomas Lindahl ◽  
Åsa Almqvist
Keyword(s):  
Human Plasma ◽  
Plasminogen Activator ◽  
Binding Protein ◽  
Gel Filtration ◽  
Plasminogen Activator Inhibitor ◽  
Stable Complex ◽  
Normal Human Plasma ◽  
Normal Human ◽  
Activator Inhibitor ◽  
Stoichiometric Complex

SummaryGel-filtration experiments of mixtures of functionally active and inactive forms of plasminogen activator inhibitor (PAI) with human plasma or bovine serum albumin have provided evidence for the existence of a discrete binding protein of PAI in plasma. Most likely it is a glycoprotein with a molecular weight of approximately 150,000. The data suggest that it forms a very stable complex with functionally active forms of PAI, but not with the inactive or “latent” PAI. However, the PAI activity seems not to be significantly altered by the interaction with the binding protein. Assuming that a stoichiometric complex is formed, titration experiments suggest that a pool of normal human plasma contains about 40–50 mg of PAI-binding protein liter.

EVIDENCE FOR A PLASMINOGEN ACTIVATOR INHIBITOR BINDING PROTEIN IN PLASMA

1987 ◽  
Author(s):  
B Wiman ◽  
T Carlsson ◽  
J Chmielewska
Keyword(s):  
Molecular Weight ◽  
Human Plasma ◽  
Plasminogen Activator ◽  
Binding Protein ◽  
Gel Filtration ◽  
Apparent Molecular Weight ◽  
Plasminogen Activator Inhibitor ◽  
Guanidinium Chloride ◽  
Pathophysiological Role ◽  
Activator Inhibitor

For several years it has been known that plasminogen activator inhibitor in plasma behaves as a high molecular weight compound on gelfiltration, in spite of that the molecular weight is only 50,000 in the presence of sodium dodecylsul-phate. The reason for this has so far been unknown. On gelfiltration of plasma, to which purified latent PAI from HT 1080 cells was added, the PAI antigen gel-filtered as a 50,000 Mr protein. However, if the latent form of PAI was reactivated by guanidinium chloride prior to the gel-filtra-tion experiment, an apparent molecular weight of about 250.000 for PAI antigen and activity was observed. If more than 10,000 U of PAI activity was added/mL of normal human plasma, excess PAI occurred at 50,000 Mr on gel-filtration. Human normalplasma was subjected to gel-filtration on sepha-cryl S-300 or Sepharose 6B and the fractions were checked for capacity to transform low Mr functional PAI to high Mr functional PAI. This capacity was only found in the 150 - 200,000 Mr region of the chromatogram. These data suggest that human plasma contains a protein that binds active forms of PAI. The complex of this protein and PAI could be dissociated by gelfiltration in the presence of 3 mol/L guanidinium chloride or 0.1 % (w/v) sodium dodecylsulphate. The physiological or pathophysiological role of the PAI-binding protein is not known. Work with purification of the protein is in progress. Considerable purification have so far been obtained by precipitation with polyethylenglycol 6000 (0-6%), gel-filtration on Sephacry1 S-300, followed by affinity chromatography on heparin-Sepharose.

Plasma Components which Interfere with Ristocetin-induced Platelet Aggregation

1975 ◽  
Vol 33 (03) ◽  
pp. 540-546 ◽  
Author(s):  
Robert F Baugh ◽  
James E Brown ◽  
Cecil Hougie
Keyword(s):  
Platelet Aggregation ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Binding Protein ◽  
Plasma Heating ◽  
Protein S ◽  
Fold Increase ◽  
Normal Human Plasma ◽  
Preliminary Examination ◽  
Normal Human

SummaryNormal human plasma contains a component or components which interfere with ristocetin-induced platelet aggregation. Preliminary examination suggests a protein (or proteins) which binds ristocetin and competes more effectively for ristocetin than do the proteins involved in ristocetin-induced platelet aggregation. The presence of this protein in normal human plasma also prevents ristocetin-induced precipitation of plasma proteins at levels of ristocetin necessary to produce platelet aggregation (0.5–2.0 mg/ml). Serum contains an apparent two-fold increase of this component when compared with plasma. Heating serum at 56° for one hour results in an additional 2 to 4 fold increase. The presence of a ristocetin-binding protein in normal human plasma requires that this protein be saturated with ristocetin before ristocetin-induced platelet aggregation will occur. Variations in the ristocetin-binding protein(s) will cause apparent discrepancies in ristocetin-induced platelet aggregation in normal human plasmas.

ON DIFFERENT MOLECULAR EORMS OE PLASMINOGEN ACTIVATOR INHIBITOR

1987 ◽  
Author(s):  
I Carlsson ◽  
J Chmielewska ◽  
B Wiman
Keyword(s):  
Conditioned Medium ◽  
Plasminogen Activator ◽  
Active Form ◽  
Sodium Dodecyl ◽  
Calf Serum ◽  
Gel Filtration ◽  
Plasminogen Activator Inhibitor ◽  
Elution Pattern ◽  
Inactive Form ◽  
Activator Inhibitor

The production of plasminogen activator inhibitor (PAI) by the human cell-lines Hep G2 and HT 1080 have been studied by immunochemical and functional methods. In conditioned medium collected after 2h, the PAI seemed to be almost fully active, but with increasing incubation time the activity was gradually lost, in spite of that the PAI-antigen content increased continously. The active PAI form can be separated from the inactive form by gel-filtration. The inactive form behaves as a low Mr (about 50,000) component in the absence and in the presence of sodium dodecyl-sulphate. In contrast, the active form of PAI behaves as a high Mr (>300,000) compound in the absence of sodium dodecylsulphate but as a low MT compound in its presence. The low M_r inactive PAI has been purified to homogeneity from HT 1080 conditioned medium, collected in the absence of fetal calf serum. This was achieved by chromatography on Concanavalin A-Sepharose, gel-filtration on Sephacryl S-300 and affinity chromatography on insolubilized monoclonal antibodies against PA-inhibitor. On treatment of this form of the inhibitor with 4 mol/L Guanidinium chloride, the activity was regained, but its gel-filtration behaviour was unchanged in the absence of serum/plasma (Mr about 50,000). Addition of plasma or serum prior to the gel-filtration, changed the elution pattern of PAI towards a high Mr form. The reason for this behaviour is not yet fully understood, but the most plausible explanation is the presence of a high Mr PAI-binding protein in plasma/serum. This hypothesis is presently being explored .

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