BIOCHEMICAL STUDIES ON THE FIBRINOLYTIC ACTIVITY OF HEMOLYTIC STREPTOCOCCI : II. NATURE OF THE REACTION.

The fibrinolysin of hemolytic streptococci exerts no hydrolytic action upon casein, gelatin, or peptone. The action on solid human fibrin is characterized by a small and gradual increase in the amino nitrogen content of the solution. The specific and special enzymatic action of fibrinolysin is contrasted with trypsin and with streptococcal peptase (4). Solutions of human fibrinogen, after brief incubation with fibrinolysin, lose the capacity to form fibrin. Solutions of rabbit fibrinogen, on the other hand, retain the property of transformation into fibrin, even after prolonged exposure to fibrinolysin. Qualitative tests, with solutions resulting from the action of streptococcal fibrinolysin on human fibrin, indicate that the end-product may be protein and that the degradation of the molecule is not great.