cytochrome P450

CYP11A1

A gene on chromosome 15q23-q24 that encodes a member of the cytochrome P450 superfamily of enzymes, which catalyse reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. CYP11A1 localises to the mitochondrial inner membrane and catalyses the conversion of cholesterol to pregnenolone, the first and rate-limiting step in the synthesis of the steroid hormones.

cytochrome P450

Abbreviation: CYP

A group of enzymes present in every type of cell in the body except red blood cells and skeletal muscle cells. They are important in metabolizing substances normally present in the body such as steroids, fat-soluble vitamins, fatty acids, prostaglandins, and alkaloids. The P450 enzymes also detoxify drugs and a great number of environmental pollutants, such as carcinogens present in tobacco smoke and charcoal-broiled meat, polychlorinated biphenyls, and dioxin. Specialized types of cytochrome P450 are involved in the synthesis of nitric oxide.

See also: cytochrome

cytochrome P450

A family of enzymes responsible for the detoxification and elimination of foreign substances including many drugs by hydroxylation and increasing their solubility. The group has been intensively studied because mutations of the cytochrome P450 gene have been found to be associated with a number of diseases including Addison's disease, liver cancer and Parkinson's disease. Cytochrome P450 can also interfere with drug treatment. Selective inhibitors of aromatase-specific cytochrome P450 have been developed to assist in the treatment of breast cancer.

cytochrome P450

hepatic microsome responsible for biotransformation of local anaesthetic agents into simpler chemical compounds