Xanthine oxidase

Xanthine oxidase is an enzyme that oxidizes hypoxanthine to xanthine and xanthine to uric acid, producing reactive oxygen species during these reactions.

Hypoxanthine: Hypoxanthine is a purine breakdown product that xanthine oxidase converts into xanthine. It is the enzyme’s first substrate in the pathway to uric acid.
Allopurinol: Allopurinol is a medication that inhibits xanthine oxidase and reduces uric acid production. It is a widely used treatment that blocks the enzyme’s catalytic activity.
Purine: Purines are nitrogen-containing compounds whose molecular framework occurs in nucleic acids and many cellular molecules. The enzyme acts on purine-derived compounds during their breakdown.
Hyperuricemia: Hyperuricemia is an abnormally high concentration of urate in blood. Increased production through this enzyme can contribute to elevated blood urate.
Xanthine: Xanthine is a purine breakdown intermediate formed from hypoxanthine and oxidized into uric acid. It is the enzyme’s second substrate in purine breakdown.
Febuxostat: Febuxostat is a medication that selectively inhibits xanthine oxidase to lower uric acid levels. It offers an alternative enzyme-inhibiting treatment for chronic hyperuricemia.
Purine metabolism: Purine metabolism comprises the synthesis, salvage, and degradation of purine nucleotides and related compounds. Xanthine oxidase catalyzes terminal reactions in the degradation branch.
Reactive oxygen stress: Oxidative stress occurs when reactive oxidants exceed the capacity of antioxidant defenses. Reactive oxygen species generated by the enzyme can contribute to oxidative stress.
Uric acid: Uric acid is the final product of purine degradation in humans and several other species. Xanthine oxidase produces it in the pathway’s final oxidation.
Gout: Gout is an inflammatory arthritis caused by monosodium urate crystal deposition in joints and tissues. Excess uric acid generated through this pathway can promote urate crystal formation.

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Gertrude B. ElionRelated: Allopurinol lowers uric acid by inhibiting this enzyme.