Plasmin dissolves the fibrin of blood clots and acts as a proteolytic factor in a variety of other processes including embryonic development, tissue remodeling, tumor invasion, and inflammation; in ovulation it weakens the walls of the Graafian follicle. It activates the urokinase-type plasminogen activator, collagenases and several complement zymogens, such as C1 and C5. It cleaves fibrin, fibronectin, thrombospondin, laminin and von Willebrand factor (By similarity). Preferential cleavage: Lys-|-Xaa > Arg-|-Xaa, higher selectivity than trypsin. Converts fibrin into soluble products. Optimum pH is 8. Optimum temperature is 40 degrees Celsius. Plasmin is inactivated by alpha-2-antiplasmin immediately after dissociation from the clot. Belongs to the peptidase S1 family. Plasminogen subfamily.