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X4875 Sigma

Xanthine Oxidase from bovine milk

Grade IV, ammonium sulfate suspension, ≥0.1 units/mg protein

Synonym: XOD, Xanthine:oxygen oxidoreductase



Analysis Note

Protein determined by biuret

General description

Formerly E.C.

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.

Physical form

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

Biochem/physiol Actions

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.

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.

Price and Availability

All labs need water

Biomedical Applications
Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 
Protocols & Articles


Ammonium Sulfate Suspensions - Technical Note

Note that for an ammonium sulfate suspension, most of the enzyme will be in solid form. It is likely that only negligible amounts of enzyme will be in the ammonium sulfate solution.
Keywords: Enzyme activity

Related Content

Enzymes & Proteins

Application Index | Enzyme Index | Substrate Index | Inhibitor Index | Cofactor Index | Lectin Index
Keywords: Cell signaling, Diagnostic, Drug discovery, Molecular biology

Peer-Reviewed Papers


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