Studies on a Proteolytic Enzyme of Barley Grain

Barley contains a proteolytic enzyme which hydrolyses the synthetic substrate, benzoyl-arginine-p-nitroanilide. This enzyme has been purified by chromatography on DEAE-cellulose and gel filtration. During purification the activity of the enzyme increased 3–10 fold, an effect which is possibly due to removal of an unstable dissociable inhibitor. The enzyme is inhibited by SH-reagents only to the extent of 50–70%. Thus the thiol group does not seem to be at the active centre of the enzyme but somewhere sufficiently close to it to interfere sterically with the formation of the enzyme-substrate complex.