Differences in effects of fibrin(ogen) fragments on the activation of 1-glu-plasminogen and 442-val-plasminogen by tissue-type plasminogen activator.

The activation rate of plasminogen by tissue-type plasminogen activator can be increased by fibrin(ogen) fragments. There is a remarkable difference in the effect of these fragments on the stimulation of 1-glu-plasminogen activation and 442-val-plasminogen (mini-plasminogen) activation. Fibrin monomer as well as plasmic fragments Y, D EGTA and D-dimer have a stimulating effect on both 1-glu-plasminogen and 442-val-plasminogen activation, whereas cyanogen bromide fragment FCB2 stimulates only the activation of 1-glu-plasminogen. Results indicate that two types of sites may be operational in fibrin and fibrin(ogen) fragments Y, D EGTA and D-dimer. One type of site (FCB2-related) interacts probably with plasminogen and may be dependent on the kringle 1-4 region; the other type of site probably interacts either with plasminogen in a non-kringle 1-4 region-dependent manner or with tissue-type plasminogen activator.