The interaction of streptokinase with human, cat, dog, and rabbit plasminogens. The fragmentation of streptokinase in the equimolar plasminogen-streptokinase complexes.

Highly purified human (Lys-forms), cat, dog, and rabbit plasminogens showed significantly different sensitivities to activation by highly purified streptokinase. The most sensitive plasminogen is the human zymogen, followed by the cat, dog, and rabbit zymogens, respectively. These human, cat, dog, and rabbit zymogens reacted with streptokinase to form homogeneous equimolar plasminogen-streptokinase complexes. The electrophoretic mobilities of the human and cat complexes on cellulose acetate were different from their respective zymogens, but the electrophoretic mobilities of the dog and rabbit complexes were similar to their respective zymogens. The human, cat, and dog complexes showed different mobilities from their respective zymogens in acrylamide gel electrophoretic systems and appeared to show multiple electrophoretic forms. With these species, all of the multiple isoelectric forms of the zymogens reacted with streptokinase. Analyses of the human (Gluand Lys-forms), cat, dog, and rabbit equimolar plasminogen-streptokinase complexes, incubated for various time intervals, in an acrylamide gel-dodecyl sulfate-urea electrophoretic system, showed the gradual conversion, or transformation, of the plasminogenstreptokinase complexes into plasmin-streptokinase complexes. These transformations occurred at different rates in each of the mammalian plasminogen-streptokinase complexes. This acrylamide gel system also permitted a comparison between the plasmin-derived carboxymethyl heavy (A) and carboxymethyl light (B) chains produced from these mammalian zymogens by two different methods of activation, namely with equal molar ratios of streptokinase to zymogen and with low molar ratios of urokinase to zymogen (1:lOOO). The carboxymethyl heavy (A* and A’) chains produced by streptokinase activation of the human (Gluforms), cat, and rabbit plasminogens in the complex appeared to have higher molecular weights than the major carboxymethyl heavy (A and Al) chains derived from each of these