Identification of molecular forms of plasminogen and plasmin-inhibitor complexes in urokinase-activated human plasma.
Urokinase-activated human plasma was analysed by acetic acid/urea/polyacrylamide-gel electrophoresis. The bands representing plasminogen, the plasmin-alpha 2-plasmin inhibitor and plasmin-alpha 2-macroglobulin complexes were identified by immunoprecipitation with specific antibodies and by comparison with purified components. Plasminogen and the plasmin-inhibitor complexes were isolated from plasma or thrombin-clotted plasma containing 125I-labelled Glu-plasminogen (residues 1-790) and urokinase. The plasma was kept at 37 degrees C for 0.5 and 10 times the lysis time of the clotted plasma, the clotted plasma until lysis. The plasmin heavy chain from the plasmin-inhibitor complexes was subsequently prepared. Only in one case could a low-grade proteolytic conversion of Glu- forms into Lys/Met/Val-forms (residues 77-790, 68-790 and 78-790 respectively) during the preparations be detected. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and N-terminal sequence analysis of the purified plasminogen and plasmin heavy chain showed the following. The plasminogen in plasma was on the Glu- form. Glu-plasmin constituted 0.74 and 0.58 of the plasmin bound to the alpha 2-plasmin inhibitor in plasma after brief and prolonged activation respectively. The rest was Lys/Met/Val-plasmin. The clotted plasma contained about equal amounts of Glu-plasminogen and Lys/Met/Val-plasminogen, and predominantly Lys/Met/Val-plasmin complexed to alpha 2-plasmin inhibitor and alpha 2-macroglobulin. The results of the analysis of the purified material substantiated the identity of radioactive protein bands in the gel after acetic acid/urea/polyacrylamide-gel electrophoresis.
D000595:Amino Acid Sequence; D000933:Antifibrinolytic Agents / Q000276:immunology / Q000378:metabolism*; D011232:Chemical Precipitation; D004591:Electrophoresis, Polyacrylamide Gel; D005341:Fibrinolysin / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D010958:Plasminogen / Q000378:metabolism*; D013820:Thermolysin / Q000097:blood; D014568:Urokinase-Type Plasminogen Activator / Q000494:pharmacology*; D000979:alpha-2-Antiplasmin; D000511:alpha-Macroglobulins / Q000097:blood
D000933:Antifibrinolytic Agents; D046911:Macromolecular Substances; D000979:alpha-2-Antiplasmin; C038528:alpha-2-macroglobulin-thermolysin complex; D000511:alpha-Macroglobulins; C037742:plasmin-plasmin inhibitor complex; D010958:Plasminogen; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D013820:Thermolysin