The iron chelator deferoxamine has been reported to inhibit both xanthine oxidase (XO) and xanthine dehydrogenase activity, but the relationship of this effect to the availability of iron in the cellular and tissue environment remains unexplored. XO and total xanthine oxidoreductase activity in cultured V79 cells was increased with exposure to ferric ammonium sulfate and inhibited by deferoxami...

An electrochemical anodic stripping procedure for ultra-trace assay of xanthine in Cu2þ solution at a glassy carbon electrode (GCE) is described. Cyclic voltammetry was used to characterize the nature of the process taking place at the GCE. The anodic stripping response in the presence of Cu2þ, at 150 mV (peak I) and 600 mV (peak II), is evaluated with respect to various experimental and instru...

Guanine tetraplexes are biological non-covalent systems stabilized by alkali cations. Thus, self-clustering of guanine, xanthine and hypoxanthine with alkali cations (Na(+), K(+) and Li(+)) is investigated by electrospray ionization mass spectrometry (ESI-MS) in order to provide new insights into G-quartets, hydrogen-bonded complexes. ESI assays displayed magic numbers of tetramer adducts with ...

During the acute phase of myocardial ischemia, adenine nucleotides are degraded to nucleosides and bases, especially inosine and hypoxanthine. Simultaneously, xanthine dehydrogenase is converted to xanthine oxidase, an enzyme that converts hypoxanthine to xanthine, and xanthine to uric acid, producing a superoxide anion for each molecule of hypoxanthine or xanthine oxidized. To determine if fre...

The free radical-generating enzyme xanthine oxidase has been hypothesized to be a central mechanism of the injury which occurs in postischemic tissues; however, its importance remains controversial. Much attention has focused on the role of this enzyme in myocardial reperfusion injury. While xanthine oxidase has been observed in ischemic tissue homogenates, the presence and importance of radica...

Xanthine dehydrogenase from the plant Arabidopsis thaliana was analyzed on molecular and biochemical levels. Whereas most other organisms appear to own only one gene for xanthine dehydrogenase A. thaliana possesses two genes in tandem orientation spaced by 704 base pairs. The cDNAs as well as the proteins AtXDH1 and AtXDH2 share an overall identity of 93% and show high homologies to xanthine de...

Xanthine oxidoreductase (XOR) catalyzes the reaction of hypoxanthine to xanthine and of xanthine to uric acid. Inhibitors of XOR can thus decrease the concentration of uric acid in serum. Crystal structures of XOR bound with various inhibitors reveal that inhibitors can be categorized into three types, i.e. mechanism-based, structure-based, and hybrid types.

In studying the oxidation of xanthine manometrically by using liver homogenate systems (l), certain irregularities in the method have become evident to the authors. Occasionally an oxygen consumption has been observed after 2 to 3 hours of incubation which is greatly in excess of the theoretical requirement for the complete oxidation of the xanthine substrate. In certain experiments the measure...

The influence of dietary protein on the activity of rat liver xanthine oxidase has been studied by several workers (l-5) and would point to a relationship between the availability of amino acids and the activity of liver xanthine oxidase (2). It has been demonstrated that the loss of liver xanthine oxidase activity in the rat greatly exceeds the loss of liver protein during acute inanition (l),...