[17 Beta-estradiol interaction with haptoglobin and its complex with hemoglobin]

The estradiol-binding capacity of sheep haptoglobin and its complex with hemoglobin was investigated. It was shown that in the presence of H2O2 the haptoglobin-hemoglobin complex tightly binds 17 beta-estradiol. No dissociation of the estradiol-protein complex occurs after its precipitation with trichloroacetic acid and steroid extraction with the ester. It is supposed that the 17 beta-estradiol is bound to the protein by covalent bonds; this binding is characteristic only of the haptoglobin-hemoglobin complex but not of haptoglobin alone.