XANTHINE-OXIDASE AS A SOURCE OF HYDROGEN-PEROXIDE FOR THE LACTOPEROXIDASE SYSTEM IN MILK

The lactoperoxidase system in milk is dependent on a source of hydrogen peroxide for its antibacterial activity. We demonstrate that this hydrogen peroxide can be derived from xanthine oxidase and a suitable substrate, hypo-xanthine. The activity of xanthine oxidase necessary for this function is less than half that normally in bovine milk. Low concentrations of free purines in combination with xanthine oxidase, lactoperoxidase, and thiocyanate indirectly give rise to a substantial antibacterial effect in bovine milk. © 1979, American Dairy Science Association. All rights reserved.