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P450-Glo™ CYP3A4 Biochemical and Cell-Based Assays
Mary Sobol, M.S, Dongping Ma, M.S, and James J. Cali, Ph.D.
Promega Corporation
The bioavailability and clearance of most therapeutic drugs are primarily mediated by cytochrome P450 enzymes, and adverse drug-drug interactions frequently occur
because of altered P450 activities. In this article, we describe cytochrome P450 assays that can predict both P450 induction-based and P450 inhibition-based drug-drug
interactions at the earliest stages of drug discovery. We focus on assays for the CYP3A4 enzyme, which accounts for about 30% of the P450 in human liver and oxidizes
about half of all drugs that are eliminated after prior metabolism. We have developed three luminogenic P450-Glo™ CYP3A4 substrates: Luciferin-BE, Luciferin-PFBE
and Luciferin-PPXE. Each substrate is used as a probe for in vitro biochemical assays of recombinant CYP3A4 to detect P450 inhibition by test compounds.
Additionally, Luciferin-PFBE is ideal for cell-based measurements of CYP3A gene inductions by drugs. The cell-based assay is rapid and simple and can be performed in a
nonlytic mode that leaves cells intact for additional analysis.
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