Carbohydrate Metabolism of Citrus Fruits II. OXIDATION OF SUGARS BY AN AERODEHYDROGENASE FROM YOUNG ORAKGE FRUITS*

Enzymes that catalyze the oxidation of glucose and other sugars directly to the corresponding aldonic acids appear to be widely distributed in nature, since they have been found in bacteria (l-9)) fungi (10, II), algae (la), and animal tissue (13-15). In a preliminary communication (16), we have reported that the juice sacs of young oranges contain a system for the oxidation of sugars to aldonic acids. The present communication contains further information on the preparation and properties of this oxidase system. It has been shown to catalyze the oxidation of at least nine different sugars and thus appears to have a much wider range of specificity than enzymes previously investigated. Various tests suggest that the oxidation of most of these sugars may occur through the action of a single enzyme with a wide substrate specificity rather than by a family of enzymes, each with a high specificity for a single substrate.