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Xanthine Oxidase (XOD)

from cow milk

Enzyme Commission number:

Quality Level

biological source

bovine milk



specific activity

~1 units/mg protein (At 25 °C with xanthine as the substrate.)


pkg of 1 mL (20 U)



optimum pH


shipped in

wet ice

storage temp.


General description

Xanthine:oxygen oxidoreductase
Xanthine Oxidase (XOD) is a metal flavoprotein. It has FAD, molybdenum and iron in the ratio 2:2:8.


Xanthine Oxidase has been used to study tyrosine nitration.
Xanthine Oxidase (XOD) has been used in the assessment of XOR-mediated NO production from NDHP and assessment of nitrite-derived NO in liver and purified XOR.

Biochem/physiol Actions

Xanthine Oxidase (XOD) exhibits a broad substrate specificity including aldehydes, purines and pteridines. Furthermore, this enzyme reduces oxygen to generate superoxide, hydrogen peroxide and reactive oxygen species (ROS). It also reduces nitrite to yield reactive nitrogen species (RNS), such as peroxynitrite and nitric oxide. Owing to its ability to generate RNS and ROS, XOD might play an important role as an antimicrobial agent in the neonatal gut, thereby complementing endogenous enzyme of the intestinal epithelium.


Contaminants: <0.005% guanase, NP and uricase, each, <0.05% ADA, <0.05% alkaline phosphatase (4-nitrophenyl phosphate as the substrate)
Note: Chromatographically purified.


XOD is a dimer. Each subunit contains 1 atom of molybdenum, 2 iron-sulfur centers (non-heme iron, ferredoxin-type) and 1 molecule of FAD.

Unit Definition

One unit (U) xanthine oxidase will produce 1 μmol of uric acid (E293nm = 12.2 mmol -1 x L x cm-1) from the oxidation of 1 μmol of xanthine in 1 min at 25 °C and pH8.5.

Physical form

Suspension in 3.2 M ammonium sulfate solution, 10 mM EDTA, pH approximately 8

Preparation Note

Activator: O2
Stabilizers: The substance is stabilized by the addition of EDTA; salicylate is not added.

Other Notes

For life science research only. Not for use in diagnostic procedures.

Storage Class Code

12 - Non Combustible Liquids



Flash Point(F)

does not flash

Flash Point(C)

does not flash

Certificate of Analysis

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Certificate of Origin

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