CARBOHYDRATE OXIDASE A NOVEL ENZYME FROM POLYPORUS OBTUSUS .2. SPECIFICITY AND CHARACTERIZATION OF REACTION PRODUCTS

1. 1. Carbohydrate oxidase, an enzyme obtained from the mycelium of the Basidiomycete Polyporus obtusus, has been shown to catalyze the oxidation of several carbohydrates at the second carbon atom to yield 2-keto products. The reactions catalyzed are as follows: 1.1. a. d-glucopyranose + O2 → d-glucosone + H2O2 1.2. b. d-xylopyranose + O2 → d-xylosone + H2O2 1.3. c. l-sorbose + O2 → 5-keto-d-fructose + H2O2 1.4. d. δ-d-gluconolactone + O2 → 2-keto-d-gluconic acid + d-araboascorbic acid + H2O2 2. 2. Other carbohydrates were tested and found not to be substrates. The structural requirements for substrate reactivity were studied. 3. 3. The oxidation of δ-gluconolactone to araboascorbic acid was shown to be inhibited by d-glucose, d-xylose and l-sorbose. 4. 4. The specificity of carbohydrate oxidase was compared with that of enzymes reported to occur in other microorganisms. © 1968.