Preparation and concentration of the pituitary gonadotropins from human plasma.

Distribution of pituitary gonadotropic activity among fractions of human postmenopausal plasma has been previously reported by the authors (I-3). When the plasma was separated into five fractions by the ethanol Method 6 of Cohn et al. (4), gonadotropic activity was found in Fraction II + III, although the other fractions were devoid of significant activity. The object of this communication is the presentation of methods for the separation from plasma and the concentration of the protein or proteins which exhibit gonadotropic activity. Two methods of preparation are described, both of them based upon the fractionation of human plasma by ethanol and zinc salts under conditions of carefully controlled ionic strength, pH, temperature, and protein concentration. One method, Gl, permits the preparation of gonadotropins without loss of other plasma proteins. Biological data obtained from the fractionation by this method of a 7 liter pool of postmenopausal plasma are presented. The other method, G2, achieves purification and concentration of gonadotropins with a minimum of manipulation but with sacrifice of other valuable plasma components. Biological data obtained by the application of Method G2 to a 10 liter pool of postmenopausal plasma have already been presented (3). Although it is not always possible to make large scale application of a laboratory technique without appreciable adaptation, the methods to be described can be so applied. The successful preparation of pituitary gonadotropin by Method Gl from 300 liters of normal human plasma’ is