Comparison of Three Substrates (Casein, Fibrin, and Gelatin) in Zymographic Gel

Three zymographic techniques using casein, fibrin, and gelatin as substrates in SDS-PAGE were compared based on three aspects: (1) The proteolytic pattern of extracellular enzymes from the three bacterial strains, Bacillus sp. DJ-1, DJ-2, and DJ-3. (2) The enzymatic sensitivity of their activity on zymogram gels. (3) The stability of stained zymogram gels with Coomassie brilliant blue in the destaining solution. There was no significant difference on the pattern of extracellular enzymes from the three strains. The bands in the fibrin gel were clearer and more distinct from the extensive destaining process. It was also shown that the gelatin gel revealed the highest enzymatic sensitivity among the three gels, based on the densitometric analysis. In the casein gel, a trace that could be mistaken as a proteolytic band appeared around 40-50 kDa.