Xanthine oxidase activity sites

The Mo atom of the molybdenum pterin cofactor addition with a terminal oxygen, a plurality of sulfur atom and connected to a terminal hydroxyl group. Xanthine to uric acid in the reaction, the oxygen on the molybdenum first transferred to the xanthine molecule, and then, the water molecules and the reactive intermediates undergo addition, so that the activity of the molybdenum center regeneration.
Molybdenum oxide with other known enzymes of the same, the product of the newly introduced oxygen atom is the oxygen from the water molecule, rather than oxygen molecules.