Energetic significance of plant monooxygenase individual components participating in xenobiotics degradation

Data obtained in this work shows that the transformation of plant cytochrome P-450 to P-420 under the action of oxygen and oxidative substrates is associated to substitution of monooxygenase activity by peroxidase. Under these conditions the oxygenase reductase component and the cytochrome b5 change their function to play a role in the respiratory chain. Thus, electrons are transferred from NADPH to the bc1-complex of a mitochondrial respiratory chain via the reductase and the cytochrome b5. In the presence of xenobiotics the reductase and cytochrome b5 switch from their energetic to their detoxification function, supplying cytochrome P-450 with NADPH reducing equivalents. Furthermore, evidence was obtained suggesting that when NADPH is deficient, electrons are transferred from complex II and III of the mitochondrial respiratory chain to cytochrome P-450.