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Updated: Aug 13, 2026
09:07
Detecting the Ligand-binding Domain Dimerization Activity of Estrogen Receptor Alpha Using the Mammalian Two-Hybrid Assay
Published on: December 19, 2018
Skeletal conformations and receptor binding of some 9,11-modified estradiols
E Palomino1, M J Heeg, J P Horwitz
1Walker Cancer Research Institute, Detroit, MI 48201.
Summary
Modifying estradiol (E2) at the 9-11 positions significantly altered its skeletal conformation and estrogen receptor binding affinity. Structural changes impacted ligand interaction, with some analogs showing drastically reduced or no binding capacity.
Area of Science:
- Medicinal Chemistry
- Structural Biology
- Molecular Pharmacology
Background:
- Estradiol (E2) is a key hormone, and understanding its structure-activity relationship is crucial for drug development.
- Modifications to the steroid nucleus can alter E2's conformation and its interaction with the estrogen receptor (ER).
Purpose of the Study:
- To investigate the impact of modifications at the 9-11 positions of estradiol on its skeletal conformation.
- To analyze the resulting changes in binding affinity to the human estrogen receptor.
Main Methods:
- X-ray crystallography was employed to determine the precise three-dimensional structures of modified estradiol analogs.
- MM2 molecular mechanics simulations were used to analyze skeletal conformations and predict structural changes.
- Estrogen receptor binding assays were performed to quantify the affinity of modified ligands.
Main Results:
- 11-hydroxyl and 11-keto analogs retained conformations similar to E2, but exhibited varied receptor affinities.
- A 9-11 double bond flattened the steroid molecule, reducing receptor binding to 1/5th of E2.
- 11 alpha-hydroxyl and 9 beta-estradiol modifications induced significant conformational changes, drastically reducing or abolishing receptor binding.
Conclusions:
- Modifications at the 9-11 positions of estradiol profoundly influence its skeletal conformation and estrogen receptor binding.
- Specific structural alterations, such as the 11 alpha-hydroxyl group or 9 beta-estradiol conformation, can lead to a loss of receptor affinity.
- Understanding these structure-activity relationships is vital for designing novel ER modulators.
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