#Question id: 15360

The cytochrome P450 constitute a superfamily of heme-containing enzymes that occur in nearly all living organisms, from bacteria to mammals, These monooxygenases, which in animals are embedded in the endoplasmic reticulum membrane, catalyze reactions of the sort

                  RH + O₂ + 2 H⁺ + 2e⁻ → ROH + H₂O 

The electrons (e−) are supplied by NADPH, which passes them to cytochrome P450’s heme prosthetic group via the intermediacy of the enzyme NADPH P450 reductase. Here RH represents a wide variety of usually lipophilic compounds for which the different cytochromes P450 are specific. They include

a. polycyclic aromatic hydrocarbons 

b. polycyclic biphenyls

c. frequently carcinogenic compounds that are present in tobacco smoke, broiled meats, and other pyrolysis products

d. which were widely used in electrical insulators and as plasticizers and are also carcinogenic.