Xanthine oxidase (EC 1.2.3.2) activity increases in liver of rabbits deficient in vitamin E. Immunochemical titration of the enzyme demonstrates that the elevation of activity is due to an increased accumulation of the enzyme protein rather than activation of preexisting enzyme molecules. Immunochemically, xanthine oxidase from deficient animals is indistinguishable from the enzyme from control...

The enzyme xanthine oxidase has been implicated as a generator of toxic oxygen metabolites that contribute to ischemic injury. Because substantial species variability has been demonstrated and because there are minimal human data available, the relevance of xanthine oxidase to human heart damage has been in doubt. We report the absence of xanthine oxidase activity in nine human heart biopsy spe...

In 1948 Keith et al. (1) demonstrated that in chicks fed a folic aciddeficient diet liver xanthine oxidase activity was far higher than that observed in birds receiving adequate levels of folic acid. It was postulated (2, 3) that 6-formylpteridine, a potent inhibitor of xanthine oxidase in vitro, was biologically active in controlling the oxidation of xanthine and hypoxanthine in vivo, since 6-...

Xanthine oxidase is a key enzyme responsible for hyperuricemia, a pre-disposing factor for Gout and oxidative stress-related diseases. Only two clinically approved xanthine oxidase inhibitors Allopurinol and Febuxostat are currently used for treatment of hyperuricemia. However, owing to their side effects there is a need for new non-purine-based selective inhibitors of xanthine oxidase. In the ...

One of the earliest studies reporting the presence of xanthine oxidase in rat skin was made by Barry et al. (1). Westerfeld and Richer-t (2), in a study of the distribution of this enzyme in the tissues of the white rat, confirmed this finding and reported that activity in the skin accounted for approximately 20% of the total xanthine oxidase of the rat. These authors did not study the enzyme i...

I . The oral administration of sodium molybdate caused a rapid rise of molybdenum in the milk of cows and goats fed on a low-molybdenum diet, but did not affect the xanthine oxidase activities of the milk of either species. 2. In the milks of cows not dosed with sodium molybdate, the regression of the xanthine oxidase activity ( y ) on the molybdenum content (x) was found to be (r = +0.9386; P ...

A new group of compounds analogous to the purines was recently described (1) in which carbon atom 2 of the purine ring was replaced by nitrogen. One of these imidazo-1 ,2,3-triazines (I), conveniently called 2-azaadenine, was shown to be an antagonist of hypoxanthine and of adenine in its toxic action against bacteria and mice. The corresponding hydroxy compound, 2-azahypoxanthine, was relative...

The oxidation of hypoxanthine to xanthine and of xanthine to uric acid is catalysed by xanthine oxidase (EC 1.2.3.2). This enzyme has been considered to be an oxidase in mammalian organs (De Renzo, 1956), whereas it is a dehydrogenase in the organs of birds, with NAD+ probably being the physiological electron acceptor (Morell, 1955a,b; Fellig & Wiley, 1958). We have reported that in freshly pre...

Molybdenum hydroxylases, aldehyde oxidase and xanthine oxidoreductase, were shown to be involved in the nitroreduction of 2-nitrofluorene (NF), 1-nitropyrene, and 4-nitrobiphenyl, environmental pollutants, in the skin of various mammalian species. NF was reduced to 2-aminofluorene by hamster skin cytosol in the presence of 2-hydroxypyrimidine, 4-hydroxypyrimidine, N(1)-methylnicotinamide, or be...