The use of isomeric testosterone dimers to explore allosteric effects in substrate binding to cytochrome P450 CYP3A4.

The use of isomeric testosterone dimers to explore allosteric effects in substrate binding to cytochrome P450 CYP3A4. J Inorg Biochem. 2015 Dec 31; Authors: Denisov IG, Mak PJ, Grinkova YV, Bastien D, Bérubé G, Sligar SG, Kincaid JR Abstract Cytochrome P450 CYP3A4 is the main drug-metabolizing enzyme in the human liver, being responsible for oxidation of 50% of all pharmaceuticals metabolized by human P450 enzymes. Possessing a large substrate binding pocket, it can simultaneously bind several substrate molecules and often exhibits a complex pattern of drug-drug interactions. In order to better understand structural and functional aspects of binding of multiple substrate molecules to CYP3A4 we used resonance Raman and UV-VIS spectroscopy to document the effects of binding of synthetic testosterone dimers of different configurations, cis-TST2 and trans-TST2. We directly demonstrate that the binding of two steroid molecules, which can assume multiple possible configurations inside the substrate binding pocket of monomeric CYP3A4, can lead to active site structural changes that affect functional properties. Using resonance Raman spectroscopy, we have documented perturbations in the ferric and Fe-CO states by these substrates, and compared these results with effects caused by binding of monomeric TST. While the binding of trans-TST2 yields results similar to those obtained with monomeric TST, the binding of cis-TST2 is much tighter and...
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research