Galactose oxidase: molecular analysis and mutagenesis studies.

Introduction Galactose oxidase (GOase; EC 1.1.3.9) is a coppercontaining enzyme that is secreted by certain filamentous fungi, and is the subject of a recent review [ 11. The most extensively studied source of the enzyme is the strain no. 2003 of the Northern Regional Research Laboratory (NKKI,) collection, Peoria, II,, lJ.S.A. [2]. This fungus is designated as Dactylium dendroides [ 3 1, however, we have recently shown that this phylogenetic assignment is wrong. I he galactose-oxidase-producing fungus that is deposited ;is IVIIKI, 2003 and as the American Type Culture Collection (Al’CC) 46032 is a Fusarium species (Z. I$. Ogel, I>. Hrayford and M. J. McI’herson, unpublished work). (;Oase displays strict substrate stereospecificity in catalysing the oxidation of a range of primary alcohols. including the C-0 position of iqgilactose, 2and 3-methyl-i )-galactose and the terminal I ) galactose of oligosaccharides, to the corresponding aldehydes. This oxidation is accompanied by the reduction of molecular oxygen and the release of hydrogen peroxide. Unusually, the enzyme contains only a single Cu(II), and yet catalyses a twoelectron-transfer reaction, which implies the existence of a second cofactor. r .