In VivoObservations on Testosterone and Estradiol-17β Protein Binding in Women

Abstract

The protein binding of radioactive testosterone and estradiol was studied following in vivo injection of the steroids. Serum samples from pregnant and nonpregnant women were partitioned sequentially by continuous paper electrophoresis, Sephadex column filtration and polyacrylamide gel electrophoresis. Non-albumin protein binding of each steroid was found to be increased during pregnancy. The protein binding patterns of testosterone and estradiol differed with respect to the proportion bound to albumin and their more specific binding protein (s). Testosterone-binding protein (TBP) and estradiol-binding protein (EBP) could not be separated in these studies. TBP-EBP had the properties of an _α2-globulin on polyacrylamide gel electrophoresis.