TRIDEGIN, A NOVEL PEPTIDIC INHIBITOR OF FACTOR XIIIA FROM THE LEECH, HAEMENTERIA-GHILIANII, ENHANCES FIBRINOLYSIS IN-VITRO

Tridegin is a potent inhibitor of factor XIIIa from the leech, Haement eria ghilianii, which inhibits protein cross-linking. It modifies plas min-mediated fibrin degradation as shown by the absence of D-dimer and approximately halves the time for fibrinolysis. Plasma clots formed i n the presence of Tridegin lyse more rapidly when either streptokinase , tissue plasminogen activator or hementin is added 2 h after clot for mation. The effect of Tridegin is markedly increased if clots are form ed from platelet-rich plasma. Platelet-rich plasma clots are lysed muc h more slowly by the fibrinolytic enzymes used and if Tridegin is pres ent, the rate of lysis returns almost to that of platelet-free clots. These studies indicate the important role of platelets in conferring r esistance to commonly used fibrinolytic enzymes and suggest that prote in cross-linking is an important step in this effect. Moreover they in dicate that Tridegin, a small polypeptide, may have potential as an ad junct to thrombolytic therapy.