Hypoxanthine oxidase is an enzyme molecule that catalyzes the oxidation of uric acid to alloxanthin (the oxidized form of uric acid). Enzyme activity is maintained when uric acid concentrations are low. In the absence of this substance, the enzyme level decreases. After it enters the human body, the cellular elements of the bone marrow begin to generate the hypoxanthine molecule and nitric oxide. A complex of hydroxylase and nitric oxide takes part in the breakdown of urinary bone to alloxucinin. Hypoxanthene oxidase carries out the first step