XANTHINE OXIDOREDUCTASE IS A KEY ENZYME OF PURINE CATABOLISM REGULATION.

Xanthine Oxidase (XO; EC 1.3.22) as well as Xanthine Dehydrogenase (XDH; EC 1.17.1.4) are two enzymes responsible for the last steps of purine metabolism, hydroxylation of a wide variety pyrimidine, pterin, and aldehyde. There are numerous publications evidencing not directly about regulating role of the hypoxanthine/xanthine existence and its catabolism in the row of the purine metabolic pathway. Activitie of XO were evaluated based on the method introduced by Litwack et all [1]. Protein quantity was calculated based on the Bradford methos. We have used Student t-test as well as ONE-WAY-ANOVA. We have chosen the best condition for evaluation of XO activity in the homogenate. The activity of XO in the rat brain in the presence of different substrates was the following in comparison with the control (1.2104±0.0000, p<0.05): for histidine 2.2190±0.4707, in the presence of allopurinol-1.6138±0.2690, for riboflavin 1.6138±0.1345 (with allopurinol - 1.4651±0.8773), for adenosine - 1.6138±0.2017 (with allopurinol - 1.2776±0.1345), for desoxyadenosine - 2.2997±0.5245, (with allopurinol - 1.2507±0.0672). We concluded, that regulation of Xanthineoxidoreductase by feedback mechanism might suppress the catabolism of purines and serves as a basis for the initiation of cells proliferative processes. [ABSTRACT FROM AUTHOR]