Cell-free extracts from nodules of cowpea (Vigna unguiculata L. (Walp.) cv Caloona:Rhizobium strain CB756) prepared in the presence of 15% (v/v) glycerol showed high rates (30 to 60 nanomoles NAD reduced per minute per gram fresh weight nodule) of inosine monophosphate oxidoreductase (EC 1.2.1.14) activity. The enzyme was labile (half-life of activity less than 3 hours) but could be stabilized ...

Nitric oxide (NO) may limit myocardial ischemia-reperfusion injury by slowing the mitochondrial metabolism. We examined whether rat heart contains catalysts potentially capable of reducing nitrite to NO during an episode of regional myocardial ischemia produced by temporary coronary artery occlusion. In intact Sprague-Dawley rats, a 15-min coronary occlusion lowered the nitrite concentration of...

Xanthine oxidoreductase (XOR) is the enzyme responsible for the final step in purine degradation resulting in the generation of uric acid. Here we have generated mice deficient in XOR. As expected, these animals lack tissue XOR activity and have low to undetectable serum levels of uric acid. Although normal at birth, XOR-/- mice fail to thrive after 10 to 14 days, and most die within the first ...

The Moco (molybdenum cofactor) sulfurase ABA3 from Arabidopsis thaliana catalyses the sulfuration of the Moco of aldehyde oxidase and xanthine oxidoreductase, which represents the final activation step of these enzymes. ABA3 consists of an N-terminal NifS-like domain that exhibits L-cysteine desulfurase activity and a C-terminal domain that binds sulfurated Moco. The strictly conserved Cys430 i...

Reactive oxygen species are generated by various systems, including NADPH oxidases, xanthine oxidoreductase (XOR) and mitochondrial respiratory enzymes, and contribute to many physiological and pathological phenomena. Mammalian xanthine dehydrogenase (XDH) can be converted to xanthine oxidase (XO), which produces both superoxide anion and hydrogen peroxide in a molar ratio of about 1:3, dependi...

The purpose of these studies was to determine the effects of uric acid (UA) and inosine administration on xanthine oxidoreductase activity in broilers. In experiment one, 25 broilers were assigned to 5 treatment groups: control, AL (25 mg of allopurinol/kg of body mass), AR (AL for 2 wk followed by allopurinol withdrawal over wk 3), UAF (AL plus 6.25 g of UA sodium salt/kg of feed), and UAI (AL...

Nitric oxide (NO) derived from the activity of neuronal nitric oxide synthase (NOS1) is involved in S-nitrosylation of key sarcoplasmic reticulum (SR) Ca(2+) handling proteins. Deficient S-nitrosylation of the cardiac ryanodine receptor (RyR2) has a variable effect on SR Ca(2+) leak/sparks in isolated myocytes, likely dependent on the underlying physiological state. It remains unknown, however,...