||In trypanosomatids have been identified glycosomal enzymes of the purine salvage pathway and the de novo pyrimidine biosynthetic pathway. In addition, in some metazoa have been identified two enzymes involved in purine metabolism in peroxisome: xanthine oxidase (XDH) and urate oxidase (UOX). XDH exist in two functionally forms, the dehydrogenase and the oxidase. The last form induces cell damage by producing reactive oxygen metabolites, and lack of its function undergoes xanthinuria. UOX catalyses the oxidation of urate, yielding hydrogen peroxides. Multiple mutations of the urate oxidase have resulted in loss of that enzyme in humans and primates.