Differential autolysis of human and canine plasmins

Abstract

Plasmin, like trypsin, undergoes autolysis. The proteolytic activity of human plasmin was virtually abolished after incubation at 37° for 1 hour, whereas the activity of the canine plasmin remained relatively stable under the same conditions. After 23 hours of incubation at 25°, canine plasmin had lost only 12% of its proteolytic activity, while human plasmin had lost 72% of its activity. Gel electrophoretic analyses showed differences in the susceptibility to proteolysis of the light and heavy chain components of the two plasmin molecules. The light chain of canine plasmin was relatively stable to autolysis while the light chain of human plasmin underwent extensive proteolytic degradation. The patterns of digestion of the heavy chain components of the two plasmin species were also found to be different. The results obtained in this study suggest that significant differences exist in the structures of human and canine plasmins.