The limited proteolysis of soluble recombinant streptokinase by Sephar
ose-immobilized human plasmin(ogen) complexed with recombinant strepto
kinase is described. A 17kDa streptokinase fragment comprising residue
s Val143 (Glu148) to Arg289 (Lys293) has been shown to be the smallest
stable plasminogen binding domain. Moreover, this region seems also t
o be important for plasminogen activation.