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-...

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...

In this study, a new method based on immobilized metal affinity chromatography (IMAC) combined with ultrafiltration-ultra performance liquid chromatography-mass spectrometry (UF-UPLC-MS) was developed for discovering ligands for xanthine oxidase (XO) in Gnaphalium hypoleucum DC., a folk medicine used in China for the treatment of gout. By IMAC, the high flavonoid content of G. hypoleucum could ...

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...