title: Steroid binding to the cytosolic estrogen receptor from rat uterus. Influence of the orientation of substituents in the 17-position of the 8 beta- and 8 alpha-series.
abstract: The exact chemical and sterical requirements in the 17-position of 8 beta- and 8 alpha-estrogens for an effective binding to the cytosolic receptor of immature rat uterus were investigated by competition experiments under non-equilibrium conditions. Oxygen or nitrogen functions with free electron pairs seem to be of essential importance in the 17-position. In contrast to 17 alpha-methyl-, -vinyl- or -ethinyl-substituents a 17 alpha-ethyl group strongly disturbs receptor binding. Also the introduction of a quasi equatorial allene or a 17 beta-ethinyl group reduces receptor binding. In comparison to the 8 beta-estrogens, the 8 alpha-derivatives always showed lower, but still significant receptor binding and similar response to changes of substituents in the 17-position.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002855:Chromatography, Thin Layer; D003600:Cytosol / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D008968:Molecular Conformation; D051381:Rats; D011960:Receptors, Estrogen / Q000378:metabolism*; D013256:Steroids / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014599:Uterus / Q000378:metabolism*
chemical_list: D011960:Receptors, Estrogen; D013256:Steroids