International biologists study on plasminogen

Plasminogen is the inactive precursor of the trypsin-like serine protease plasmin. It is normally found circulating through the blood stream. When plasminogen becomes activated and is converted to plasmin, it unfolds a potent enzymatic domain that dissolves the fibrinogen fibers that entgangle the blood cells in a blood clot.
When a fibrin blood clot is present in the bloodstream, Plasminogen is attracted to the clot. The clot acts almost as a place to sequester the plasminogen long enough for its activator, most commonly tPA, to convert plasminogen into plasmin. Whe plasminogen is activated, it unfolds to expose its potent enzymatic domains. In the above picture, the plasminogen is being sequestered by plasminogen Binding Material, or PBM. PBM was developed in research to find another material that plasminogen could bind to in order to activate plasmin in significant amounts. PBM serves as an alternative activation source. PBM is generally used in such implants as vascular implants, where fibrin buildup could become a problem. It is put on these implants as a coating, and is used on surfaces of metals, polymers, valve coatings, stents and catheters.
The activated or open form of plasminogen( http://www.cusabio.com/ELISA_Kit-96960/ ) exposes its many kringles. The kringles are responsible for facilitating protein-protein interactions between plasmin and fibrin. Kringles 1,2,4 and 5 have been shown to display such interactions. Plasminogen attacks fibrin at least 50 different sites. When this occurs, plasmin cleaves the fibers into many fragments, reducing the size of the fibers until they can no longer retain their function of entangling blood cells. Among these fragments are fragments called D-dimers. A D-dimer is a protein that represents an area of fibrin which contain cross-linked regions used as clot stabilizers. D-dimer present in circulation is used as an indicator of a blood clot being formed and broken down somewhere in the body.