2CKJ OXIDOREDUCTASE, FAD, NAD, IRON, 2FE-2S, MOLYBDENUM, PEROXISOME, REVERSIBLE INTERCONVERSION, XANTHINE DEHYDROGENASE, XANTHINE OXIDOREDUCTASE, XANTHINE OXIDASE, IRON- SULFUR, POLYMORPHISM, FLAVOPROTEIN, METAL-BINDING HUMAN MILK XANTHINE OXIDOREDUCTASE