Not available outside of the UK & Ireland.

Analysis Note

Protein determined by biuret

Application

Xanthine Oxidase from bovine milk has been used:in the preparation of xanthine oxidase (XO) solution for 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO)-spin trapping assayin invitro XO assay for screening Vietnamese medicinal plants for XO inhibitory activityas a standard to determine XO activityas a standard to test the synergistic effect of docosahexaenoic acid (DHA)

Biochem/physiol Actions

Xanthine oxidase was shown to be involved in the reduction of cytochrome c by the generation of superoxide anions following the oxidation of xanthine. These free radicals are responsible for reducing cytochrome c.

Hydroxylation of hypoxanthine to xanthine and xanthine to uric acid is catalyzed by xanthinebb oxidase (XO) enzyme.

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.

General description

Formerly E.C. 1.1.3.22

Xanthine Oxidase (XOD) is a metal flavoprotein. It has flavin adenine dinucleotide (FAD), molybdenum and iron in the ratio 2:2:8. This homodimer has a molecule weight of 290kDa. It is a member of the molybdenum-protein family. This enzyme consists of two separated substrate-binding sites.

Packaging

5, 25 units in serum bottle

Physical form

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

Unit Definition

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.