Xanthine Oxidase from bovine milk

Research area: Cell CycleXanthineoxidase (XO) is a homodimer. It is made up of two sub-units each made up of onemolybdenum and two iron-sulphur (2Fe-2S) centers.

Formerly E.C. 1.1.3.22

Xanthine Oxidase from bovine milk has been used in superoxide dismutaseactivity assay.Xanthine oxidase may be suitable for producing amperometric biosensors and designing-flavonoid-type inhibitors against XO for treating inflammatory diseases, gout, and hyperuricemia. It may also be used in the synthesis of superoxide because of aldehyde oxidation.

Xanthine oxidase is a molybdenum-containing enzyme that is found in the cytosol, and may be strongly inhibited by flavonoids. It plays a vital role in the metabolism of some drugs, as well as purines and pyrimidines. It is also known to be a biological source of reactive oxygen species.

Although xanthine oxidase is found widely distributed in multiple tissues, it is highly expressed in endothelial and epithelial cells. Its expression was also increased in infected tissues where it was shown to have an anti-microbial effect due to its ability to generate reactive oxygen species. Xanthineoxidase plays an important role in catalyzing the hydroxylation ofhypoxanthine to Xanthine. Later, xanthine is converted to uric acid isexcreted by the kidneys.

Suspension in 2.3 M (NH₄)₂SO₄ containing 1 mM sodium salicylate

Protein determined by biuret

One unit will convert 1.0 μmole of xanthine to uric acid per min at pH 7.5 at 25 °C. Approx. 50% of the activity is obtained with hypoxanthine as substrate.