Galactose Oxidase - A Radical Enzyme that Catalyzes Radical Reactions to Generate Radical Products

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The wood rot fungus Dactylium dendroides excretes large amounts of the enzyme galactose oxidase (GOase) into the extracellular medium1. GOase has been classified as an alcohol oxidase, using O2 to convert primary alcohols (RCH2OH) into aldehydes (RCHO) and H202. GOase can react with a wide variety of primary alcohols, includingmany carbohydrates, such as glucose, cellobiose, maltose, lactose, sucrose, and polymeric carbohydrates, including cellulose. Although the oxidase reaction of GOase has been known for decades, the main biological purpose of GOase has always been a puzzle. Recent work in the Branchaud laboratory indicates that GOase possesses multiple activities, including an iron reductase activity. Fe(II) produced by the iron reductase activity and H202 from the oxidase activity could combine to produce hydroxyl radicals via the Fenton reaction. The PI proposes that the principle activity of GOase in nature is to generate hydroxyl radicals for the purpose of breaking down wood cellulose and other complex polymers. The research examines and characterizes the multiple activities of this enzyme. %%% Galactose oxidase produces hydroxyl radical, one of the reactive, broad specificity oxidants known. Such a biocatalyst has potential application in oxidatively degrading complex biomolecules in toxic wastes and in developing more environmentally friendly bleaching technologies.