Rat-intestinal dextranase. Localization and relation to the other carbohydrases of the digestive tract

Abstract

The intestinal dextranase in confined to the small-intestinal mucosa. Like the disaccharidases it is chiefly particulate in mucosal homogenates, but can be solubilized with trypsin without appreciable loss of activity. The distribution of the dextranase and the results of fractionation (by anion-exchange chromatography and heat inactivation) demonstrated that the dextranase is distinct from amylase, invertase, trehalase and at least the major part of the maltase activity. Isomaltase, in contrast, was indistinguishable from the dextranase with a constant isomaltase dextranase activity ratio of 2.0. It is suggested that these two activities are exerted by the same enzyme. The amylase activity of mucosal preparations was found to belong to two different enzymes. The disaccharidase activities were exerted by a mixture of enzymes, roughly similar to those previously recognized in preparations from pig- and humanrsmall-intestinal mucosa, but showing a species difference in containing two invertases.