Association of sexual hormones with nucleobases in water: NMR-investigations.

The mixed association of testosterone-sulfate and estradiol-sulfate with several derivatives of nucleobases in D2O has been investigated by means of nuclear magnetic resonnance spectroscopy. From the differences among the chemical shifts of the hormone-protons it is concluded, that the nucleobases in the complexes are located above the center of the steroid molecule. The beta-side of the steroid which is characterized by the axial methyl-groups is directed towards the bases. The enthalpies of mixed association of the hormones with a certain nucleobase of the same order of magnitude as the enthalpy of selfassociation of this nucleobase (Schimmack et al., to be published). It is suggested that the complexes are stabilized by van-der-Waals forces. This stacking-like interaction is not specific for the male or female sex hormones: no qualitative or quantitative differences have been observed among the complexes of the two hormone-sulfates with the nucleobases.