<unk>  is a superoxide-producing enzyme found normally in serum and the lungs, and its activity is increased during influenza A infection. During severe liver damage,<unk>  is released into the blood, so a blood assay for<unk>  is a way to determine if liver damage has happened. Because<unk>  is a metabolic pathway for uric acid formation, the<unk>  inhibitor allopurinol is used in the treatment of gout. Since<unk>  is involved in the metabolism of 6-mercaptopurine, caution should be taken before administering allopurinol and 6-mercaptopurine, or its prodrug azathioprine, in conjunction.<unk> ria is a rare genetic disorder where the lack of<unk>  leads to high concentration of<unk>  in blood and can cause health problems such as renal failure. There is no specific treatment, sufferers are advised by doctors to avoid foods high in purine and to maintain a high fluid intake. Type I<unk> ria has been traced directly to mutations of the XDH gene which mediates<unk>  activity. Type II<unk> ria may result from a failure of the mechanism which inserts sulfur into the active sites of<unk>  and aldehyde<unk> , a related enzyme with some overlapping activities (such as conversion of allopurinol to oxypurinol). Inhibition of<unk>  has been proposed as a mechanism for improving cardiovascular health. A study found that patients with chronic obstructive pulmonary disease (COPD) had a decrease in oxidative stress, including glutathione oxidation and lipid peroxidation, when<unk>  was inhibited using allopurinol. Oxidative stress can be caused by hydroxyl free radicals and hydrogen peroxide, both of which are byproducts of<unk>  activity. Increased concentration of serum uric acid has been under research as an indicator for cardiovascular health factors, and has been used to strongly predict mortality, heart transplant, and more in patients. But it is not clear whether this could be a direct or casual association or link between serum uric acid concentration (and by proxy,<unk>  activity) and cardiovascular health. States of high cell turnover and alcohol ingestion are some of the most prominent cases of high serum uric acid concentrations. Reactive nitrogen species, such as peroxynitrite that<unk>  can form, have been found to react with DNA, proteins, and cells, causing cellular damage or even toxicity. Reactive nitrogen signaling, coupled with reactive oxygen species, have been found to be a central part of myocardial and vascular function, explaining why<unk>  is being researched for links to cardiovascular health. Both<unk>  and<unk>  oxidoreductase are also present in corneal epithelium and endothelium and may be involved in oxidative eye injury.
Xanthine oxidase
Aldehyde oxidase
Thymidine phosphorylase
Aldehyde dehydrogenase
Transaminase
Biotinidase
Phenylalanine hydroxylase
Asparaginase