1. The catalytic properties of xanthine oxidase in bovine milk (EC 1.2.3.2) are dependent on the state of the enzyme, i.e. whether free or bound to the fat-globule membrane. Oxidase activity of the membrane-bound enzyme towards NADH is enhanced relative to that towards xanthine. This reflects a change in the relative K(m) values and enables the ratio of xanthine to NADH oxidase activities (X/N)...

T HE ENZYME, XANTHINE OXIDASE, is thought to play a central role in the mobilization of storage iron from the liver.1 In the presence of xanthine oxidase, xanthine is oxidized to uric acid, the enzyme acting as electron acceptor in the oxidation reaction . ‘ Coupled to the oxidation of uric acid is the reduction of ferric ferritin to the ferrous state. The livers of immature rats contain very l...

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...

We directly measured the activity of the enzymes xanthine oxidase and xanthine dehydrogenase in rabbit and rat hearts, using a sensitive radiochemical assay. Neither xanthine oxidase activity nor xanthine dehydrogenase activity was detected in the rabbit heart. In the rat heart, xanthine oxidase activity was 9.1 +/- 0.5 mIU per gram wet weight and xanthine dehydrogenase activity was 53.0 +/- 1....

the purpose of the given work was to study the dairy efficiency of the delivered, local and crossbreed goats in three different generations (f1, f2 and f3), derived from their crosses, as well as the biochemical composition of milk and some bloodplasma hormones, participating in the process of lactopoez. for the biochemical tests of milk we have selected casein and serumproteins, iron in lactof...

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...

Xanthine oxidase is a member of molybdoenzyme family and has catalytic role in purine degradation, metabolizing hypoxanthine and xanthine to uric acid with the generation of superoxides. In the present study, microtitre plate based colorimetric assay was used to screen the xanthine oxidase producing microorganisms from the soil treated with hypoxanthine with different concentrations (2mM, 4mM, ...

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...

The distribution of xanthine dehydrogenase throughout the soybean plant as well as the intercellular localization of xanthine dehydrogenase within soybean nodules was determined. Polyclonal antibodies against purified xanthine dehydrogenase were prepared and used in an enzymelinked immunosorbent assay to determine whether xanthine dehydrogenase is a nodule-specific protein. This immunological a...