Inhibitory Antibodies to Human Cytochromes

Human cytochrome P450s play a prominent role in the metabolism of steroids, fatty acids,eicosanoids, drugs, phytochemicals and toxins. Specific enzymes can activate carcinogens, can beinduced, stimulated or inhibited by various compounds, and can be one of several polymorphic forms.Although the enzymic properties measured using animal P450s are suggestive of what might beexpected from closely related human enzymes, these reagents/systems are nonetheless imprecisepredictors of the catalytic range and sensitivity associated with a particular human P450. We areaddressing this deficiency. The long range goal is the development of suitable reagents and assaysystems that can readily evaluate human P450 mediated metabolism. A method for producing sitespecific, high affinity, inhibitory antibodies will be valuated. These antibodies will be capable ofrecognizing both denatured and native, membrane bound P450 antigen. Such reagent will allow reactionhenotyping of specific P450 forms in a complex mixture such as human liver microsomes and providea valuable tool for assessing changes in tissue oncentration resulting from exposure to inducing agents.In addition, a method is described for producing a panel of expressed epitopes form closely relatedP450s that will be obtained from various human cDNA libraries. This epitope panel will be used to assesantibody cross reactivity as well as to identify new and previously uncharacterized P450 enzymes.These immunoregents will help delineate the myriad possibilities for interaction between this complexenzyme family and a vast array of pharmaceutical, environmental and dietary compounds. Thisknowledge can be essential for predicting drug-drug interactions and the impact of genetic deficiencieson toxicity.