Purified Active Xanthine Dehydrogenase Enzyme

Xanthine Dehydrogenase Ref. #E-Nov11
Quantity	Price*
1 Unit	€ 275.00
2 Units	€ 440.00
5 Units	€ 1030.00
* Pricing updated December 14^th, 2013 Provided in stable lyophilized form and shipped without dry ice To buy active XDH enzyme click here or ask for Quotation

Xanthine Dehydrogenase from bovine milk (XDH, EC 1.17.1.4)

NOVOCIB's XDH is a native lyophilized enzyme extracted from bovine milk by solvent extraction and affinity purification procedures.

Xanthine oxidoreductase (XOR) catalyzes the formation of uric acid from hypoxanthine and xanthine, last two steps of purine catabolism. The mammalian enzyme is synthesized as a xanthine dehydrogenase form (XDH, EC 1.17.1.4), which uses NAD as the electron acceptor, but is converted into an xanthine oxidase form (XO, EC 1.1.3.22) by reversible (through sulfhydryl group oxidation) or irreversible (proteolysis) manner. Since most industrial protocols of XOR purification includes proteolysis step, commercial XOR enzyme is available only as oxidase form unable to use NAD as a an electron acceptor.

In contrast to these products, NOVOCIB's xanthine dehydrogenase enzyme is purified under conditions that preserved the activity of the enzyme so its capacity to reduce NAD as a result of hypoxanthine/xanthine oxidation.

Unit Definition: One unit of XDH catalyzes the reduction of 1µmol of NAD per minute at pH 8.8 with concomitant oxidation of hypoxanthine to uric acid.

References:
1. T. Nishino et al. (2005): Mechanism of the conversion of xanthine dehydrogenase to xanthine oxidase: identification of the two cysteine disulfide bonds and crystal structure of a non-convertible rat liver xanthine dehydrogenase mutant. J Biol Chem. 280(26):24888-94.
2. T. Nishino, T. Nishino. (1997): The conversion from the dehydrogenase type to the oxidase type of rat liver xanthine dehydrogenase by modification of cysteine residues with fluorodinitrobenzene. J Biol Chem. 272(47):29859-64.
3. Harrison R.(2002): Structure and function of xanthine oxidoreductase: where are we now? Free Radic Biol Med. 33(6):774-97.
4. C. Enroth et al (2000) Crystal structures of bovine milk xanthine dehydrogenase and xanthine oxidase: Structure-based mechanism of conversion . PNAS 97(20): 10723–10728.

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