Previous chemical work directed toward isolation of the thyrotropic hormone from the anterior pituitary (usually bovine) has almost always depended upon precipitation methods of purification (Janssen and Loeser, 1931; Junkmann and Schoeller, 1932; Loeser, 1932; Greep, 1935; Lambie and Trikojus, 1937; Bonsnes and White, 1940; Fevold et al., 1940; Fraenkel-Conrat et al., 1940; Ciereszko, 1945). A number of reagents used in the fractionation of various proteins have been applied to crude extracts; thyrotropin has been found to be soluble in dilute but precipitated in concentrated aqueous solutions of common organic solvents (Janssen and Loeser, 1931; Junkmann and Schoeller, 1932; Loeser, 1932; Bonsnes and White, 1940; Fraenkel-Conrat et al., 1940; Ciereszko, 1945) and salts (Fevold et al., 1940; Fraenkel-Conrat et al., 1940), and it has been precipitated by various organic acids, heavy metal salts, and other protein precipitants (Loeser, 1932). Lack of both specificity and selectivity is the essential limita...
Read full abstract