Cytochrome P-450 Enzyme System. CYP450 Family . CYP450 Superfamily . Cytochrome P-450 Enzymes . Cytochrome P-450 Families . Cytochrome P-450 Monooxygenase . Cytochrome P-450 Oxygenase . Cytochrome P-450 Superfamily . Cytochrome P450 . Cytochrome P450 Superfamily . Cytochrome p450 Families . P-450 Enzymes . P450 Enzymes . Cytochrome P 450 . Cytochrome P 450 Dependent Monooxygenase . Cytochrome P 450 Enzyme System . Cytochrome P 450 Enzymes . Cytochrome P 450 Families . Cytochrome P 450 Monooxygenase . Cytochrome P 450 Oxygenase . Cytochrome P 450 Superfamily . Enzymes, Cytochrome P-450 . Enzymes, P-450 . Enzymes, P450 . Monooxygenase, Cytochrome P-450 . Monooxygenase, Cytochrome P-450-Dependent . P 450 Enzymes . P-450 Enzymes, Cytochrome . Superfamily, CYP450 . Superfamily, Cytochrome P-450 . Superfamily, Cytochrome P450 . Cytochrome P-450 . Cytochrome P-450-Dependent Monooxygenase . 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. . 1.00