The term cytochrome P450-containing monooxygenase enzyme systems refers to a family of heme proteins present in all mammalian cell types, except mature red blood cells and skeletal muscle cells, which catalyze the oxidation of a wide variety of structurally diverse compounds. Cytochrome P450 also occurs in procaryotes. Substrates for these enzyme systems include endogenously synthesized compounds such as steroids, fatty acids (including prostaglandins and leukotrienes), and compounds such as drugs, food additives, or industrial byproducts that enter the body through food sources, injection, inhalation from the air, or absorption through the skin. Drug biotransformation by cytochrome P-450 enzymes is one of the most important systems for drug metabolism. This system can be altered by a number of mechanisms, such as induction and inhibition, and can vary significantly among individuals. P450's are proteins of 400 to 530 aminoacids. Based on sequence similarities, P450's have been classified into about forty different families. The cytochrome P450 system has far reaching effects in medicine. It is involved in: (a) inactivation or activation of therapeutic agents, (b) conversion of chemicals to highly reactive molecules, which may produce unwanted cellular damage, cell death, or mutations, (c) participation in several steps in steroid hormone biosynthesis, and (d) metabolism of fatty acids and their derivatives. [Journal of Turgut Özal Medical Center 1996;3(3):257-275]
Key Words: Cytochrome P-450, enzyme, iron-sulphur proteins, biotransformation, detoxification
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