Identification of 17 beta-estradiol as the estrogenic substance in Saccharomyces cerevisiae.

Publisher Website
Google Scholar
Abstract
S. cerevisiae possesses a high-affinity estrogen binding protein and an endogenous ligand that displaces [3H]estradiol from both the yeast binding protein and mammalian estrogen receptors. The purification procedure and ultimate identification of the estrogenic substance in extracts of S. cerevisiae as 17.beta.-estradiol are described. Organic solvent extracts of commercially obtained dried yeast were sequentially chromatographed on silica gel columns and then subjected to a series of reversed phase HPLC [high performance liquid chromatography] fractionations. Active ligand was monitored by [3H]estradiol displacement in a rat uterine cytosol assay. After 7 chromatography steps, the purified and highly active ligand exhibited a single peak with retention times identical to those of 17.beta.-estradiol on both HPLC and GC [gas chromatography]. The yeast material was identified as 17.beta.-estradiol by its UV absorbance and mass spectrometric fragmentation pattern. In addition, radioimmuoassay confirmed the presence of approximately the same mass of 17.beta.-estradiol (.apprxeq. 800 ng/1.5 kg of yeast) as estimated both by a competitive binding assay with estrogen receptor and by mass spectrometry. Extraneous contamination by estradiol was excluded by repeat experiments with different batches of starting material and demonstration of estradiol by RIA in conditioned medium and cell pellets of laboratory-grown S. cerevisiae whereas non-conditioned medium did not possess the steroid. 17.beta.-Estradiol is a yeast product.