culture media of Bacillus strains isolated from Doen-Jang, the Korean traditional fermented food. The reverse fibrin autography (Fig. 2A) shows two broad bands barely visualized on the fibrin/agar indicator gel (Fig. 2B). On the other hand, several polypeptides possessing fibrinolytic activity are detected as sharp, clear bands on the fibrin zymogram (Fig. 2B). Molecular markers are also perceptible by eye; they do not photograph well, though. It has been demonstrated that at least four fibrinolytic enzymes with apparent molecular sizes of approximately 64, 53, 38, and 29 kDa are secreted from each of two Bacillus strains isolated from Doen-Jang. The purification and characterization of the proteases will be described elsewhere.
Even though gelatin and casein are satisfactory substrates for plasmin (7, 8), all fibrinolytic enzymes are not sensitive for the substrates as much as plasmin is. Apparently fibrin is an in vivo substrate for plasmin. We took advantage of this fact to explore the possibility of assaying plasmin-like enzymes with fibrin zymography, an electrophoretic technique in which fibrin is copolymerized with the acrylamide during casting of the separating gel. We have demonstrated that the zymographic technique can be used reliably for the rapid qualitative evaluation of plasmin-like enzymes, which have the ability to restore enzymatic activity on the gel copolymerized with fibrin upon removal of the SDS, with a sensitivity level comparable to that of other zymographic techniques.