Extraction and purification of corticotropin.

The existence of a pituitary hormone which regulates the mammalian tdrenal cortex was first demonstrated by Smith (1) in 1927; the implantaion of pituitary glands restored to normal the atrophic adrenal cortices of lypophysectomized rats. Enlargement of the adrenals following t.he inection of pituitary extracts was observed by Houssay et al. (2) in the hylophysectomized dog and by Collip, Anderson, and Thomson (3) in the rypophysectomized rat. Collip et al. found the corticotropic hormone to le unusually stable to heat and to be difficult to extract and to purify. Qnsehnino, Hoffmann, and Herold (4) also concluded that the hormone is &able to heat and concluded that it, unlike other anterior pituitary hornones, would pass an ultrafilter. This conclusion, though based upon issays with non-hypophysectomized animals, was substantiated by Tyslowitz (5) and by Cortis-Jones, Crooke, Henly, Morris, and Morris (6), Ising improved methods of corticotropin assay. Of the various extraction procedures which have been applied to obtain solutions of the active principle the more successful have involved vigorous treatment of the fresh or acetone-dried pituitary tissue. Thus, Fevold, Lee, Hisaw, and Cohn (7), employing the classical methods of protein chemistry, obtained low yields of corticotropin from sheep pituitaries, and Chow, Greep, and van Dyke (S), using a saline extract and salting-out procedures followed by dialysis, could barely detect corticotropin in their extracts of pig pituitaries. Collip (9) obtained more active materials by extraction with 80 per cent ethanol or 70 per cent acetone at pH 2.5, while Bates, Riddle, and Miller (10) employed alkaline aqueous ethanol. Lyons’ successful procedure (ll), involving 83 per cent acetone and strong hydrochloric acid, was subsequently used by Li, Evans, and Simpson (12) and by Sayers, White, and Long (13) to obtain a pure protein which was considered to represent the true hormone. None of the published procedures has permitted the recovery of corticotropin in good yield, and no methods have been described for the prep-