Oxygen cytochrome P450 monooxygenation

Though the investigation of photocatalytic oxygenations performed of the laboratory scale are often motivated by attempts to understand and mimic the catalytic cycle of cytochrome P450 (a natural catalyst of monooxygenation reactions), the results obtained [159, 253, 266] could be applied to industrial processes as well. 

Monooxygenation reactions involve the reduction of one atom of molecular oxygen to water and the incorporation of the other oxygen atom into the substrate [Eq. (9.1)]. The electrons involved in the reduction of CYP are transferred from NADPH by another enzyme called NADPH-cytochrome P450 oxidoreductase (CYPOR). 

Monooxygenations are those oxidations in which one atom of molecular oxygen is reduced to water while the other is incorporated into the substrate. Microsomal monooxygenation reactions are catalyzed by nonspecific enzymes such as the flavin-containing monooxygenases (FMOs) or the multienzyme system that has cytochrome P450s (CYPs) as the terminal oxidases. 

Cytochrome P450 enzymes use molecular oxygen to create ROS that monooxygenate many natural and xenobiotic species. With natural species and some foreign chemicals, the oxygenation is helpful, producing metabolites that are eliminated from the body. With others, however, such as aromatic hydrocarbons, the ROS metabolites are far more toxic than the parent compounds and create OS. Aerobic life is dependent upon the formation and deactivation of ROS. OS arises when ROS are formed at a rate that exceeds the rate of deactivation. 

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