Zymography with caseogram prints: quantification of pepsinogen

In caseogram prints, a type of zymogram which is designed for the detection of acid proteases, enzyme activity is detected in an overlay gel of agarose containing skim milk. The use of this technique for protease quantification was investigated in this study using pepsinogen as an example protease. The area of caseogram bands was found to be logarithmically related to protease activity whereas the intensity of the bands was no reliable measure for activity. A reproducible quantification procedure was described. Accuracy and variation were acceptable over a 128-fold range whose lower border was the detection limit (35 pg pepsinogen).