The Activity of α-Amylase as Determined by Adsorption Indicators

Abstract

This note presents initial results showing that dextrinogenic activity may be detd. by measuring the loss of binding capacity of the substrate for a simple dye. A similar procedure was previously used for determining proteolytic activity, and apparently the principle can be applied generally for hydrolytic enzymes. The method consists of hydrolyzing the substrate by the enzyme under test and using a dye as indicator which undergoes a spectral change when it is adsorbed by the substrate. As the substrate is hydrolyzed, its affinity for the bound dye is altered. For determining salivary amylase activity, Congo Red was used as the dye. It has the advantage over I, that it is adsorbed by dextrins that fail to give a color response with I. When the amylase was added to a soln. of Lintner''s starch, the starch gradually lost its combining capacity for the Congo Red until the optical density, measured spectrophotometrically, for the dye alone was attained.