On the Alcohol Solubility of Prolactin by Gerhard A. Fleischer

The various methods of extracting and purifying prolactin, the lactogenie hormone of the anterior pituitary gland, are based at least in part on the observation that this hormone is soluble in 60 per cent ethanol (pH 10) and 85 per cent acetone (pH 1.5), while most of the accompanying inert proteins are not (l-4). Alcohol and acetone of higher concentration, however, will precipitate the hormone from these solutions. In the course of experiments on the purification of prolactin the surprising observation was made that this protein hormone becomes highly soluble in 99.8 per cent methanol and 95 per cent ethanol as well as in certain other organic solvents if the pH is adjusted appropriately. In view of the fact that up to date only a few alcohol-soluble proteins have been described it was thought desirable to learn more about this unusual behavior of prolactin. In the present report the results of investigations with purified hormone preparations will be presented first, followed by a description of experiments with fresh pituitary glands.’