Xanthine oxidase is a critical enzyme in the metabolic pathway of purines, which are nitrogen-containing compounds found in many foods. It catalyzes the oxidation of hypoxanthine to xanthine and then to uric acid, which is excreted in the urine. This enzyme plays a pivotal role in the catabolism of purine nucleotides into uric acid, a process that is essential for maintaining the body's nitrogen balance.
