Enzymatic Studies on the Oxidation of Sugar and Sugar Alcohol

1.An enzyme catalyzing the oxidation of L-sorbose by either oxygen or 2,6-dichlorophenol indophenol was purified about 25-fold from extracts of a basidiomycete, Trametes sanguinea. 2. The reaction with oxygen as acceptor was formulated as; L-sorbose+O2→5-keto-D-fructos+H2O2. In addition to L-sorbose, this preparation oxidized D-glucose, D-galactose, and D-xylose, but was inactive towards D-fructose and polyols. 4. The optimal pH was about 5.7 to 6.0 in potassium phosphate buffer. 5. Km values for L-sorbose were determined to be 2.2×10−2M with atmospheric oxygen as acceptor and 1.0 X 10-1M with 2,6-dichlorophenol indophenol as acceptor at pH6.0 and 30°C. 6. The L-sorbose oxidase activity was strongly inhibited by Ag+ and Hg++, but not by typical sulfhydryl reagents such as p-chloro-mercuribenzoate and phenylmercuric nitrate.