Effects of alcohols and ligands on estrogen receptor dimer exchange

CHED 826

Michele M. Mumaw, mumawmm@rose-hulman.edu and Mark E. Brandt, brandt@rose-hulman.edu. Department of Chemistry, Rose-Hulman Institute of Technology, 5500 Wabash Ave., CM 1231, Terre Haute, IN 47803
The estrogen receptor is a conformationally flexible protein, which exhibits cooperativity and functional alterations in response to ligand binding. During characterization of the estrogen receptor ligand-binding domain (LBD), we recently discovered that low concentrations of organic solvents also perturb LBD functional properties in a solvent composition-dependent fashion. Ligand binding is known to decrease the rate of LBD dimer exchange, while the presence of low concentrations of short-chain monofunctional alcohols increases the rate. To further characterize these phenomena, we tested the effects of simultaneous addition of alcohols and ligands such as estradiol on the dimer exchange process. The results suggest that the alcohol counteracted the effect of ligands on the dimer exchange rate in a concentration dependent fashion. This suggests that in spite of the much lower binding affinity of the alcohols to the LBD, physiologically achievable alcohol concentrations may exhibit biological effects on the estrogen receptor.