Purification of Xanthine Oxidase from Human Milk

Abstract

Following evidence (Granger et al., 1981) that xanthine oxidase could be a source of Superoxide free radicals, responsible for ischaemia-reperfusion damage in the gut, a similar role for this enzyme has been proposed in many other tissues. Thus, xanthine oxidase has become a focus of interest as a source of free radicals also in myocardium (Thompson-Gorman and Zweier, 1991), joints (Blake et al., 1989), and liver (Brass et al., 1991). The proposed pathogenic mechanism involves ischaemia-induced proteolytic conversion of the naturally-occurring dehydrogenase form of the enzyme to its oxidase form. Concurrently, ischaemia also leads to degradation of nucleotides in the affected tissue and to accumulation of hypoxanthine. Subsequent reperfusion then provides oxygen, which, in the presence of hypoxanthine and xanthine oxidase, is reduced to hydrogen peroxide and Superoxide anion. These reactive species, together with hydroxyl radicals derived from them are the proposed agents of tissue damage.KeywordsXanthine OxidaseHuman MilkBovine MilkXanthine Oxidase ActivityXanthine DehydrogenaseThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.