Further studies with xanthine oxidase inhibitors.

The osidase and dehydrogenase activities in the enzymes oxidizing xanthine can be differentiated by the use of certain inhibitors (1). The present study was designed to see if such inhibitors are specific for the reaction with oxygen, or whether these agents also block the transfer of electrons to cytochrome c and nitrate. Both reduced diphosphopyridine nucleotide and hypoxanthine were studied as substrates because they represent separable activities in the xanthine enzymes.