Binding of Steroid Hormones and Anabolic Agents to Bovine Sex-Hormone Binding Globulin

Summary Binding of some selected steroids and anabolic agents to bovine sex-hormone binding globulin (SHBG) * was investigated. SHBG binding affinities, relative to the reference hormone 5α-dihydrotestosterone, were estimated for the compounds. The results demonstrate that binding of steroid hormones to SHBG is facilitated by the 17β-hydroxyl group, possibly involving hydrogen binding, and by the methyl group at C-19 of the steroid moiety. Structural modifications at C-17 of a steroid molecule involving esterification, epimerization or reduction of the 17β-hydroxyt group, or introduction of a bulky 17α group have the effect of decreasing the SHBG binding affinity of the steroid molecule.