Plasminogen interactions with immobilized fibrinogen.

This report describes the binding of plasminogen to fibrinogen adsorbed onto polystyrene wells. Binding was determined by enzyme linked immunosorbent assay. Both glu- and lys-plasminogen bound to immobilized fibrinogen in a dose-dependent fashion. However, more lys- than glu-plasminogen bound when equal concentrations of either were added to immobilized fibrinogen. Plasminogen binding was inhibited by epsilon aminocaproic acid indicating that binding was mediated via lysine-binding regions of plasminogen. Soluble fibrinogen added in excess of immobilized fibrinogen did not compete for plasminogen binding but fibrinogen fragments produced by plasmin digestion of fibrinogen did. Treatment of immobilized fibrinogen with thrombin caused a small but significant (p less than 0.01) increase in plasminogen binding. These studies demonstrate that immobilized fibrinogen binds both glu- and lys-plasminogen and that binding is mediated via lysine-binding regions. These interactions may facilitate plasminogen binding to fibrinogen adsorbed on to surfaces and to cells such as platelets which bind fibrinogen.