The influence of substrate unfolding on the caseinolytic activity of trypsin

Hydrolytic activity of bovine trypsin was measured in the presence and absence of urea using alpha-N-benzoyl-DL-arginine p-nitroanilide and casein as substrates. The peptidase activity measured with alpha-N-benzoyl-DL-arginine p-nitroanilide decreased in 3.1 M urea due to probable denaturation of the enzyme. In contrast, the caseinolytic activity of trypsin showed a marked increase in presence of urea. The latter observation was attributed to the probable unfolding of the substrate, i.e., casein, by 3.1 M urea.