Protease activity and autodigestion (autolysis) assays using Coomassie blue dye binding

A new proteolytic assay is described involving Coomassie blue. Under specified conditions, the amount of Coomassie-stained casein protein hydrolyzed by several proteases was proportional to the amount of protease. Coomassie dye reaction was used directly to determine the change in protein concentration of the substrate casein during proteolysis by three proteases: stem bromelain, papain, and trypsin. This method can be used with 0.1- to 0.5-micrograms quantities of protease. The dye reagent was used directly on the protease protein in order to obtain an assay of autodigestion. Autodigestion of bromelain at 50 and 25 degrees C was followed by measuring the amount of residual protease protein with time.