Purification and characterization of intracellular galactose oxidase from Dactylium dendroides

The intracellular galactose oxidase from Dactylium dendroides was purified to homogeneity with a 64% yield. The enzyme is a glycoprotein (7.7% neutral sugars, 1.7% aminosugars) with 72,000 Da of molecular mass. The enzyme showed nonlinear double reciprocal plots with O2 and D-galactose, suggesting cooperative binding for both substrates. The intracellular galactose oxidase catalyzes the oxidation of galactose derivatives and dihydroxyacetone but not of glycerol, glycolaldehyde, beta-hydroxipyruvate, and allyl alcohol which are substrates for the extracellular enzyme. Compared with the extracellular galactose oxidase, the intracellular enzyme showed higher carbohydrate content and sensitivity to diethyldithiocarbamate.