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.

Synonyms: Enzymes, P-450, Cytochrome P 450 Enzyme System, Enzyme, P-450, 9035-51-2, Cytochrome P-450, P-450 Enzymes, Cytochrome P450 Superfamily, Superfamily, CYP450, Cytochrome P-450 Monooxygenase, Cytochrome P-450 Oxygenase, Superfamily, Cytochrome P450, P 450 Enzymes, Cytochrome P 450 Enzymes, Enzymes, Cytochrome P-450, P 450 Enzyme, CYP450 Family, Cytochrome P 450 Superfamily, Cytochrome P-450 Superfamily, Cytochrome p450 Families, Cytochrome P-450-Dependent Monooxygenase, Cytochrome P 450, Enzyme, P450, CYP450 Superfamily, Monooxygenase, Cytochrome P-450, Superfamily, Cytochrome P-450, Cytochrome P 450 Monooxygenase, Cytochrome P450, Cytochrome P-450 Enzymes, Cytochrome P 450 Dependent Monooxygenase, Cytochrome P-450 Families, Cytochrome P 450 Oxygenase, P450 Enzymes, P-450 Enzyme, Cytochrome, Monooxygenase, Cytochrome P-450-Dependent, Cytochrome P 450 Enzyme, Cytochrome P-450 Enzyme System, 0, P450 Enzyme, Cytochrome P-450 Enzyme, P-450 Enzymes, Cytochrome, Enzymes, P450, Cytochrome P 450 Families, P-450 Enzyme, Enzyme, Cytochrome P-450