RGDFAP - PLATELET-AGGREGATION INHIBITORY AND PROFIBRINOLYTIC HYBRID PEPTIDE (RGDF COUPLED WITH THE CARBOXY-TERMINAL PART OF ALPHA(2)-ANTIPLASMIN) ENHANCES PLASMINOGEN BINDING TO PLATELETS

As published in a recent issue of Blood Coagulation and Fibrinolysis, the hybrid peptide RGDFAP, composed of RGDF (Arg-Gly-Asp-Phe) coupled to a synthetic peptide residue of the carboxy terminal part of antipla smin (AP(26)) inhibited platelet activation and augmented plasmin gene ration and in vitro fibrin clot lysis. This peptide contains an RGD mo tif which provides linkage to platelet GP IIb-IIIa. The antiplasmin pa rt of the molecule may attach free plasminogen, which in turn increase s the amount of platelet surface bound plasminogen, probably yielding enhanced lytic action at the site of thrombus formation. This hypothes is was investigated and confirmed by the results of platelet-plasminog en binding assays, using FITC-labelled antiplasmin antibodies and radi oligand binding analysis. Increased platelet-linked plasminogen was de tected by a chromogenic method, along with the acceleration of in vitr o lysis of platelet-rich clots in the presence of RGDFAP peptide.