Detection,quantification, and characterization of proteases in recombinant Escherichia coli

Electrophoresis of crude cell extracts on PAGE gels in the presence of SDS copolymerized with a nonspecific protease substrate has been used to detect, characterize, and quantify intracellular proteases in recombinant Escherichia coli. After electrophoresis, the gels are incubated, SDS is removed, and protease activity is revealed by clear zones on the stained gel due to proteolysis of the nonspecific protease substrate (gelatin or casein). The method differentiates proteases based on activity and molecular weight.