<b><i>Arxula adeninivorans</i></b> Recombinant Guanine Deaminase and Its Application in the Production of Food with Low Purine Content

Purines of exogenous and endogenous sources are degraded to uric acid in human beings. Concentrations >6.8 mg uric acid/dl serum cause hyperuricemia and its symptoms. Pharmaceuticals and the reduction of the intake of purine-rich food are used to control uric acid levels. A novel approach to the latter proposition is the enzymatic reduction of the purine content of food by purine-degrading enzymes. Here we describe the production of recombinant guanine deaminase by the yeast <i>Arxula adeninivorans</i> LS3 and its application in food. In media supplemented with nitrogen sources hypoxanthine or adenine, <i>guanine deaminase</i> (<i>AGDA</i>) gene expression is induced and intracellular accumulation of guanine deaminase (Agdap) protein occurs. The characteristics of the guanine deaminase isolated from wild-type strain LS3 and a transgenic strain expressing the <i>AGDA</i> gene under control of the strong constitutive <i>TEF1</i> promoter were determined and compared. Both enzymes were dimeric and had temperature optima of 55°C with high substrate specificity for guanine and localisation in both the cytoplasm and vacuole of yeast. The enzyme was demonstrated to reduce levels of guanine in food. A mixture of guanine deaminase and other purine degradation enzymes will allow the reduction of purines in purine-rich foods.