Comparison of proteases in normal and metaplastic human stomach mucosa

The proteases in normal and metaplastic human stomach mucosa were examined by preparing zymograms of tissue extracts with tosyl-L-lysine-alpha-naphthyl ester and L-prolyl-L-phenylalanyl-L-arginine-alpha-naphthyl ester as substrates. With both substrates, the zymogram of metaplastic mucosa showed an additional band (Rf 0.64) not present with normal mucosa. This band was also observed with extracts of normal small intestine and cancerous stomach tissue. It disappeared on treatment of the preparations with leupeptin, but not with esterastin.