Cytochrome P-450 Enzyme System
| Definition: |
A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. |
| Notes: |
GEN or unspecified; prefer specific cytochrome P-450's; /biosyn /physiol permitted |
| Also Called: |
Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase |
| CAS Type 1 Name: |
CAS Number: |
9035-51-2 |
| Previously Indexed: |
Cytochromes (1966-1972) |
Cytochrome P-450 Enzyme System Categories.
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Aryl Hydrocarbon Hydroxylases - A large group of cytochrome P-450 (heme-thiolate) monooxygenases that complex with NAD(P)H-FLAVIN OXIDOREDUCTASE in numerous mixed-function oxidations of aromatic compounds. They catalyze hydroxylation of a broad spectrum of substrates and are important in the metabolism of steroids, drugs, and toxins such as PHENOBARBITAL, carcinogens, and insecticides. |
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Camphor 5-Monooxygenase - A soluble cytochrome P-450 enzyme that catalyzes camphor monooxygenation in the presence of putidaredoxin, putidaredoxin reductase, and molecular oxygen. This enzyme, encoded by the CAMC gene also known as CYP101, has been crystallized from bacteria and the structure is well defined. Under anaerobic conditions, this enzyme reduces the polyhalogenated compounds bound at the camphor-binding site. |
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Steroid Hydroxylases - Cytochrome P-450 monooxygenases (MIXED FUNCTION OXYGENASES) that are important in steroid biosynthesis and metabolism. |
Cytochrome P-450 Enzyme System Definitions and Terms
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