The Specific Mechanism of Activation of Human Plasminogen to Plasmin

Abstract

Abstract The activation of human plasminogen in a 25% glycerol medium was carried out with low molar ratios of urokinase, streptokinase, trypsin, and pig heart activator. Starch gel electrophoresis in 8 m urea at pH 3.2 showed that each of the four plasmins possessed the same electrophoretic mobility. Upon reduction with 2-mercaptoethanol in 8 m urea, each plasmin was found to contain two major, electrophoretically unique components. Determination of the aminoterminal and the carboxyl-terminal amino acid residues of these plasmins indicated, in accordance with our previous studies, that the activation of human plasminogen proceeds primarily through the cleavage of a single arginyl-valine bond. Each of the plasmins contains two polypeptide chains connected by a disulfide bond.