Proteolytic resistance conferred to fibrinogen by von Willebrand factor

Anna Tanka-Salamon, K. Kolev, R. Machovich, Erzsebet Komorowicz

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The formation of platelet-rich thrombi under high shear rates requires both fibrinogen and von Willebrand factor (VWF) as molecular adhesives between platelets. We attempted to describe the role of VWF as a potential substrate and modulator of the fibrinolytic system using binding assays, as well as kinetic measurements on the cleavage of fibrin(ogen) and a synthetic plasmin substrate (Spectrozyme-PL). The similar dissociation constants for the binding of plasminogen, plasmin, and active site-blocked plasmin onto immobilised VWF suggest that the primary binding site in plasmin(ogen) is not the active site. The progressive loss of clottability and generation of degradation products during fibrinogen digestion with plasmin were delayed in the presence of VWF at physiological concentrations, while VWF cleavage was not detectable. Determination of kinetic parameters for fibrinogen degradation by plasmin, miniplasmin and microplasmin showed that VWF did not modify the Km, whereas kcat values decreased with increasing VWF concentrations following the kinetic model of non-competitive inhibition. Inhibitory constants calculated for VWF were in the range of its physiological plasma concentration (5.4 μg/ml, 5.7 μg/ml and 10.0 μg/ml for plasmin, miniplasmin and microplasmin, respectively) and their values suggested a modulating role of the kringle 5 domain in the interaction between VWF and (mini)plasmin. VWF had no effect on the amidolytic activity of plasmin on Spectrozyme-PL, or on fibrin dissolution by (mini)plasmin. Our data suggest that VWF, while a poor plasmin substrate relative to fibrinogen, protects fibrinogen against degradation by plasmin preserving its clottability in plasma and its adhesive role in platelet-rich thrombi.

Original languageEnglish
Pages (from-to)291-298
Number of pages8
JournalThrombosis and Haemostasis
Volume103
Issue number2
DOIs
Publication statusPublished - Feb 2010

Fingerprint

Fibrinolysin
von Willebrand Factor
Fibrinogen
Blood Platelets
Fibrin
Adhesives
Catalytic Domain
Thrombosis
Kringles
Plasminogen
Digestion
Binding Sites

Keywords

  • Fibrinogen
  • Fibrinolysis
  • Plasmin
  • Thrombolysis
  • Von willebrand factor

ASJC Scopus subject areas

  • Hematology

Cite this

Proteolytic resistance conferred to fibrinogen by von Willebrand factor. / Tanka-Salamon, Anna; Kolev, K.; Machovich, R.; Komorowicz, Erzsebet.

In: Thrombosis and Haemostasis, Vol. 103, No. 2, 02.2010, p. 291-298.

Research output: Contribution to journalArticle

Tanka-Salamon, Anna ; Kolev, K. ; Machovich, R. ; Komorowicz, Erzsebet. / Proteolytic resistance conferred to fibrinogen by von Willebrand factor. In: Thrombosis and Haemostasis. 2010 ; Vol. 103, No. 2. pp. 291-298.
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