Xanthine oxidase: an efficient promoter of the iron loading of apoferritin

Xanthine oxidase exhibits ferroxidase activity and previously has been shown to catalyze the oxidative incorporation of iron into apotransferrin, the iron transport protein of plasma. These studies demonstrate that xanthine oxidase also efficiently promotes the oxidative incorporation of iron into apoferritin, the major iron storage protein of vertebrates, and that the ferroxidase activity of intestinal xanthine oxidase could be important in determining the fraction of iron within the intestinal mucosa cell partitioned to ferritin versus the iron that remains in a transient pool for rapid transport to plasma.