Tissue activator-mediated plasminogen activation is potentiated both by fibrin and by some soluble fibrin(ogen) fragments. The potentiating effect of the different fragments decreases in the order fibrin monomer > D-dimer > Y > D EGTA > Dcate > X. Fibrinogen and the fragments Ecate, E EGTA and E fibrin have almost no effect. The existence of a fibrin polymer is apparently not a prerequisite for this potentiating effect. The plasminogen activation by various urokinase preparations is not potentiated by fibrin and fibrin(ogen) fragments. Chemicals/CAS: fibrin, 9001-31-4; fibrinogen, 9001-32-5; plasminogen activator, 9039-53-6; plasminogen, 9001-91-6; thromboplastin, 9035-58-9; urokinase, 139639-24-0; Fibrin Fibrinogen Degradation Products; Fibrin, 9001-31-4; fibrinmonomer; fibrinogen D fragment; fibrinogen fragment E; fibrinogen fragment X; fibrinogen fragment Y; Fibrinogen, 9001-32-5; Plasminogen Activators, EC 3.4.21.-; Plasminogen, 9001-91-6; Thromboplastin, 9035-58-9; Urinary Plasminogen Activator, EC 3.4.21.73