Xanthine Accumulation during Hypoxanthine Oxidation by Milk Xanthine Oxidase

A kinetic study of hypoxanthine oxidation by milk xanthine oxidase.

The course of the reaction sequence hypoxanthine----xanthine----uric acid catalysed by xanthine:oxygen oxidoreductase from milk was investigated on the basis of u.v. spectra taken during the course of hypoxanthine and xanthine oxidations. It was found that xanthine accumulated in the reaction mixture when hypoxanthine was used as a substrate. The time course of the concentrations of hypoxanthin...

Xanthine oxidase catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid as follows

The enzyme is well-suited to carry out the catalysis of these oxidative reactions, containing as it does four redox-active sites: molybdenum, flavin adenine dinucleotide (FAD) and a pair of iron-sulfur centers of the ferredoxin type (Fe2S2). The purine substrates interact with the enzyme at the molybdenum site of xanthine oxidase and oxygen at the flavin site. The two metabolic reactions above ...

Luminescence during the oxidation of hypoxanthine by xanthine oxidase in the presence of dimethylbiacridylium nitrate.

During the course of some studies on xanthme oxidase it was discovered that when the enzyme was incubated with one of its substrates in the presence of either lO , lO’-dimethyl-9,9’-biacridylium nitrate or 5-amino-2,3-dihydrophthalazine-l , 4-dione(luminol)light was produced in considerably greater intensity than would be expected from the rate of production of Hz02 and the known chemiluminesce...

Steps in the oxidation of xanthine to uric acid catalysed by milk xanthine oxidase.

The reduction of cytochrome c by hypoxanthine and xanthine oxidase.

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