The reaction of xanthine and xanthine oxidase generates superoxide and hydrogen peroxide. In contrast to earlier works, recent spin trapping data (Kuppusamy, P., and Zweier, J.L. (1989) J. Biol. Chem. 264, 9880-9884) suggested that hydroxyl radical may also be a product of this reaction. Determining if hydroxyl radical results directly from the xanthine/xanthine oxidase reaction is important fo...

The following evidence has led to the conclusion that xanthine oxidase, with its usual electron donors, is capable of reducing nicotinamide N-oxide to nicotinamide. 1. The purest enzyme fraction from hog liver which catalyzes the reduction has the spectrum of a metalloflavoprotein and has xanthine oxidase activity. 2. The enzyme responsible for the reduction cofractionates with hog liver xanthi...

Xanthine oxidase is a highly versatile and ubiquitous complex molybdoflavoprotein, which controls the rate limiting step of purine catabolism pathway. Microbial xanthine oxidase can be used to address a number of questions presently not feasible with the eukaryotic enzymes. In the present study, a high-throughput microtitre plate-based colorimetric assay for xanthine oxidase producing microorga...

Quantitative alterations in the purine catabolic enzyme, xanthine oxidase, have been observed in neoplasia and nonmalignant hyperplasia. A decrease in the xanthine oxidase level per cell during carcinogenesis in both liver and breast tumors has been reported (1, 8). Likewise, Bennett and associates ~ have shown that several experimental tumors are low in xanthine oxidase activity. In contrast, ...

The antitumor effect of oxygen radicals produced by hypoxanthine and xanthine oxidase reaction was studied in an experimental rabbit model. VX2 carcinomas were transplanted into rabbit hind legs. Hypoxanthine was administered continuously through the ear vein, while xanthine oxidase was administered simultaneously through the femoral artery. As a result, hypoxanthine and xanthine oxidase reacte...

The effect of cold storage (5 C, 24 h) and heat treatment (60 C, 5 min) of milk on activities of free and membrane-bound xanthine oxidase has been studied. Both treatments enhanced total xanthine oxidase activity in milk. Activity of membrane-bound xanthine oxidase increased and free xanthine oxidase decreased in buttermilk while it increased in skim milk on cold storage. Heat of milk increased...

the major objective of the present study was to characterize the effects of oxidants generated b xanthine (x) plus xanthine oxidase (xo) on isolated rat ileum motility. the effects of three concentrations of x/xo on the basal tone of the rat ileum preparation were studied for 20 minutes. developed tensions were measured in mg/mg tissues and then expressed as percentage of baseline tension. also...

OBJECTIVE Crimean-Congo hemorrhagic fever is an acute viral hemorrhagic fever with a high mortality rate. Despite increasing knowledge about hemorrhagic fever viruses, little is known about the pathogenesis of Crimean-Congo hemorrhagic fever. In this study, we measured serum adenosine deaminase and xanthine oxidase levels in Crimean-Congo hemorrhagic fever patients. METHODS Serum adenosine de...

That flavonoids inhibit xanthine oxidase from cow milk was confirmed by measuring oxygen consumption with an oxygen electrode. In contrast, flavonoids did not inhibit glucose oxidase, another oxygen consuming enzyme. Among the flavonoids tested, quercetin, kaempferol, myricetin, chrysin, quercitrin, and morin were potent inhibitors of xanthine oxidase; their inhibition rates (%) were 80, 70, 69...