[Characteristics of the estrogen receptor system of the oviducts in guinea pigs].

Kinetic and thermodynamic parameters of the estradiol receptor (E2-R) interact in the guinea pig oviduct cytozol were studied. Specificity of the receptor system was characterized by measurment of the affinity of 14 compounds to the system. It was shown that the guinea pig oviduct R-system had a high affinity to E2 and a limited capacity. Free energy change value (52 KJ/mol) indicated stability of the complex formed. Activity of the steroid-receptor (S-R) complex formation is determined by the presence of the intact hydroxils in positions 3 (phenolic) and 17-beta of the steroid molecule; dependence of the S-R interaction rate on the different steroid molecule modifications at a number of positions supports this point. Besides, the immediate enviroment of hydroxils in positions 3 and 17 beta also influences the S-R interaction rate. Some properties of the nonsteroid diethylstilbestrol estrogen attract attention.