The enzymic degradation of pectin and other polysaccharides. II—Application of the ‘Cup‐plate’ assay to the estimation of enzymes

Abstract The agar ‘cup‐plate’ diffusion technique has been applied to the quantitative determination of enzyme activity, principally to amylase, polygalacturonase, cellulase, protease and pectin‐esterase. With all enzymes so far examined, the relationship between diameter of zone and log(amount of enzyme) is linear over a wide range, and may be used for the quantitative estimation of the enzymes. The cup‐plate assay of polygalacturonase, like viscometric methods, measures the initial destruction of the colloidal properties of pectic acid, and, owing to the complex nature of polygalacturonase, bears no simple relationship to the assay of polygalacturonase by the estimation of glycosidic hydrolysis.