title: The activation of plasminogen by Hageman factor (Factor XII) and Hageman factor fragments.
abstract: Activation of plasminogen through surface-mediated reactions is well recognized. In the presence of kaolin, purified Hageman factor (Factor XII) changed plasminogen to plasmin, as assayed upon a synthetic amide substrate and by fibrinolysis. Kinetic studies suggested an enzymatic action of Hageman factor upon its substrate, plasminogen. Hageman factor fragments, at a protein concentration equivalent to whole Hageman factor, activated plasminogen to a lesser extent. These protein preparations were not contaminated with other agents implicated in surface-mediated fibrinolysis. Diisopropyl fluorophosphate treatment of plasminogen did not inhibit its activation by Hageman factor. These studies indicate that Hageman factor has a hitherto unsuspected function, the direct activation of plasminogen.
mesh_terms: D000577:Amides / Q000097:blood; D005174:Factor XII / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005342:Fibrinolysis; D006801:Humans; D066298:In Vitro Techniques; D010446:Peptide Fragments / Q000494:pharmacology; D010960:Plasminogen Activators
chemical_list: D000577:Amides; D010446:Peptide Fragments; D005174:Factor XII; D010960:Plasminogen Activators