Galactose oxidase

Galactose oxidase (GAO) is a enzyme that catalyzes the oxidation of primary alcohols to aldehydes. The enzyme is unique in that it contains a copper-tyrosine radical cofactor, which is essential for its catalytic activity.

Structure

The structure of galactose oxidase is a monomer with a molecular weight of approximately 68,000 daltons. The enzyme contains a single copper ion and a tyrosyl radical, which are both essential for its catalytic activity. The copper ion is coordinated by two histidine residues, a tyrosine residue, and a cysteine residue. The tyrosyl radical is formed by the oxidation of a tyrosine residue that is adjacent to the copper-binding site.

Function

Galactose oxidase catalyzes the oxidation of primary alcohols to aldehydes in the presence of molecular oxygen, which is reduced to hydrogen peroxide. The enzyme is highly specific for galactose and other aldose sugars, and does not act on glucose or other ketose sugars. The reaction catalyzed by galactose oxidase is important in the metabolism of galactose and in the synthesis of glycoconjugates.

Applications

Due to its ability to oxidize primary alcohols to aldehydes, galactose oxidase has potential applications in biotechnology, including the production of biofuels and the synthesis of fine chemicals. The enzyme is also used in biosensors for the detection of galactose and other aldose sugars.

See also

• Oxidoreductase
• Galactose metabolism
• Biocatalysis