Energetic significance of plant monooxygenase individual components participating in xenobiotics degradation

Data obtained in this work shows that the transformation of plant cytochrom e P-450 to P-420 under the action of oxygen and oxidative substrates is ass ociated to substitution of monooxygenase activity by peroxidase. Under thes e conditions the oxygenase reductase component and the cytochrome bs change their function to play a role in the respiratory chain. Thus, electrons ar e transferred from NADPH to the bc(1)-complex of a mitochondrial respirator y chain via the reductase and the cytochrome bs. In the presence of xenobio tics the reductase and cytochrome b(5) switch from their energetic to their detoxification function, supplying cytochrome P-450 with NADPH reducing eq uivalents. Furthermore, evidence was obtained suggesting that when NADPH is deficient, electrons are transferred from complex II and III of the mitoch ondrial respiratory chain to cytochrome P-450. (C) 1999 Published by Elsevi er Science Ltd. All rights reserved.