Characterization of human cytochrome P450 enzymes.

Many biochemical approaches have been applied to the human cytochrome P450 enzymes, and more than 20 different gene products have been characterized with regard to their properties and catalytic specificities. The complement of the various cytochrome P450 enzymes in a given individual varies markedly, and dramatic differences may be seen in drug metabolism, pharmacological response, and susceptibility to toxic effects. An understanding of the nature of the individual cytochrome P450 enzymes and their regulation should be useful in determining the most suitable animal models, ascertaining risk from chemicals, and in avoiding undesirable drug interactions.