On the significance of the cytochrome P-450-dependent hydroxyl radical-mediated oxygenation mechanism.

1. Reconstituted membrane vesicles containing purified preparations of cytochrome P-450 LM2 and NADPH-cytochrome P-450 reductase effectively destroyed 2-deoxy-D-ribose in an NADPH-dependent process. 2. The destruction was mediated by hydroxyl radicals formed in an iron-catalysed Haber-Weiss reaction between superoxide anions and hydrogen peroxide liberated from the haemoprotein. 3. Administration of ethanol or benzene to rabbits, compounds known to be oxygenated by the hydroxyl radical-dependent mechanism, resulted in induction of a species of cytochrome P-450 effective in the radical-dependent metabolism of both chemicals. 4. Benzene treatment of rabbits also resulted in an enhanced hydroxyl radical-dependent metabolism of ethanol and benzene in liver microsomes. 5. It is suggested that, for certain substrates, hydroxyl radical-mediated cytochrome P-450-dependent oxygenation reactions are of importance for the microsomal metabolism of these compounds. 6. It is speculated that radical-producing species of cytochrome P-450 may contribute to hydroxyl radical-mediated cell damage.