Human Plasminogen protein, His tag

Plasminogen (PLG) as a zymogen releases plasmin from the liver into the systemic circulation. Plasmin is a serine protease that acts to dissolve fibrin blood clots. Apart from fibrinolysis, plasmin proteolyses proteins in various other systems: It activates collagenases, some mediators of the complement system and weakens the wall of the Graafian follicle (leading to ovulation). It cleaves fibrin, fibronectin, thrombospondin, laminin, and von Willebrand factor. Plasmin, like trypsin, belongs to the family of serine proteases. Besides, Insulin Like Growth Factor Binding Protein 3 (IGFBP3) has been identified as an interactor of PLG, thus a binding ELISA assay was conducted to detect the interaction of recombinant human PLG and recombinant human IGFBP3. Briefly, PLG were diluted serially in PBS, with 0.01% BSA (pH 7.4). Duplicate samples of 100 μl were then transferred to IGFBP3-coated microtiter wells and incubated for 2h at 37ºC. Wells were washed with PBST and incubated for 1h with anti-PLG pAb, then aspirated and washed 3 times. After incubation with HRP labelled secondary antibody, wells were aspirated and washed 3 times. With the addition of substrate solution, wells were incubated 15-25 minutes at 37ºC. Finally, add 50 μl stop solution to the wells and read at 450nm immediately. The binding activity of PLG and IGFBP3 was in a dose dependent manner.