Distribution and unspecific protein binding of the xenoestrogens bisphenol A and daidzein.

Physiological toxicokinetic (PT) models are used to simulate tissue burdens by chemicals in animals and humans. A prerequisite for a PT model is the knowledge of the chemical's distribution among tissues. This depends on the blood flow and also on the free fraction of the substance and its tissue:blood partition coefficients.

A low-molecular-weight cytosolic inhibitor of the specific testosterone binding in bovine seminal vesicles.

Bovine seminal vesicle cytosol contains a low-molecular-weight and thermostable substance which specifically inhibits the binding of testosterone to its cognate receptor. The mass and the ether phospholipid structure of the inhibitor were elucidated by mass spectrometry. Saturation and binding experiments indicate that the inhibitor acts in a dose-dependent and competitive manner, altering the apparent dissociation constant (K(D)) while maintaining the number of androgen-binding sites (B(max)).