Analysis of the low affinity high capacity estrogenic binding in human benign prostatic hypertrophy

The binding of estradiol in extracts of human benign prostatic hypertrophy (BPH) tissue was studied using the agar gel electrophoretic method. Two distinct binding peaks were observed having the same high specificity for natural estrogens and very poor affinity for the other classes of steroids as well as for diethylstilbestrol (DES). Therefore, it is highly probable that these peaks are two different forms of the low affinity binding protein present in human prostate. Cytosols were shown to contain smaller amounts of the binding proteins than the tissular extracts. This difference probably resulted from protein degradation occurring during the time required to prepare the cytosol. The concentrations of the extract and of the radiolabeled ligand, the composition of the buffer, the addition of sodium molybdate, sodium tartrate or proteolytic inhibitors, were evaluated in order to delineate optimal binding conditions. The possible function of these low-affinity high-capacity binding proteins is discussed.