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Gerard Marx, Matti Ben-Moshe, Sholomo Magdassi, Raphael Gorodetsky
Fibrinogen C-terminal peptidic sequences (Haptides) modulate fibrin polymerization
We previously described synthetic peptides of 19-21 amino acid residues, homologous to the C-termini of fibrinogen Fib340 and Fib420, from the -chain (C), the extended E chain (CE) and near the end of the -chain (preC) which elicited attachment (haptotactic) responses from mesenchymal cells. We named these haptotactic peptides -Haptides. The effects of Haptides on fibrin clot formation was evaluated and their possible effects on platelet aggregation was examined. The Haptides C,CE and preC, (2-10 M) increased fibrin clot turbidity and also decreased thrombin-induced clotting time. Higher concentrations (>120 M of C or preC) induced fibrinogen precipitation even without thrombin. These precipi-tates exhibited different ultrastructure from thrombin-induced fibrin by scanning and transmission microscopy. C-terminal peptides of the other fibrinogen chains exerted no such effects. Sepharose beads covalently coated with either whole fibrinogen or Haptides (SB-Fib or SB-Haptide) highly adsorbed free FITC Haptides. In aqueous solution, Haptides formed nano-par-ticles with average size of 150nm in diameter. We suggest that such positively charged aggregates could serve to nucleate and accelerate fibrin gel formation. These results also indicate that C and preC sequences within fibrin(ogen) participate in the docking and condensation of fibrin(ogen) during its assembly into a fibrin clot. By contrast, Haptides up to 100M did not bind to platelets, and had no effect on platelet aggregation. Our findings highlight the roles of the C-terminal sequences of the and chains in fibrin(ogen) polymerization as well as in cell attachment.
Thrombosis and Haemostasis, Schattauer
Print ISSN: 0340-6245
Volume: 91, 01/2004
Pages: 043 - 051