Affinity and Conformation of the Estrogen Receptor When Bound to Single-Stranded vs. Double-Stranded Nonspecific DNA

Abstract

The affinity of the hormone-bound estrogen receptor for single-stranded and double-stranded DNA was compared using isocratic elution chromatography. The receptor bound single-stranded DNA with a two-fold higher affinity than double-stranded DNA (17.9 × 10⁴ M^?1 vs. 9.1 × 10⁴ M^?1) at 0.2 M KCl. The same number of ions were released when the receptor bound either single-stranded or double-stranded DNA (11.8 vs. 10.6, respectively). These results indicate the hormone-bound estrogen receptor has no strong preference for single-stranded vs. double-stranded nonspecific DNA, and has a similar conformation when bound to either form of DNA at physiological salt concentrations.