Summary
1. Incubated mixtures of plasminogen and streptokinase revealed three components in optical electrophoresis at pH 2.00. The fastest component was identified as plasmin, and the other two components were taken to represent plasminopeptides A and B, in accordance with their mobilities.
2. By means of gel filtration, it was possible to show the presence of three constituents. The major one had caseinolytic activity, while the other two had no such activity.
3. From the known properties of molecular exclusion by various Sephadex preparations, it was estimated that the two peptides had molecular weights of approximately 10,000.
4. The possibility of improving the purity of plasmin preparations was demonstrated.