Studies on pituitary adrenocorticotrophin. 1. Ultrafiltration of the hormone

Chemistry of the Nonsteroid Hormones

“…It was found that the protein hormone could be kept at 100°C, in 1 M HCI for 25 min. (66) suppor t the inference (74,75,76) that the ACTH activity is asso ciated with units sm aller than the proteins isolated by the earlier procedures of Li et al (68), and of Sayers et al (67). The acid-heat treatment was found useful in abolishing the activity of posterior pituitary contami nants in ACTH preparations (71).…”

“…with no loss of ACTH activity; further heating caused a ' total destruction of the potency. (76) reported that the total biological activity of the protein hormone of Sayers et al is ultrafiltrable in 0.1 M sodium acetate-acetic acid at pH 3.9. In addition, an enhancement of ACTH potency was achieved (72,73).…”

Localization of Adrenocorticotropic Hormone by Histochemical and Immunochemical Methods

“…The materials originally described as pure ACTH (18,19) were proteins of molecular weight around 20,000. On the other hand, fractions of much higher hormone potency have been isolated by various methods and found to have average molecular weights in the range of 1200 to 10,000 (12,(20)(21)(22). Smith, Brown, Ghosh, and Sayers (23) have reviewed the properties of the earlier preparations and have concluded that these may be the hormone as it is stored in the gland.…”

The activity of enzymic and acidic digests of insulin

“…In spite of this lack of success with insulin and in degradative studies on the proteolytic enzymes themselves (Northrop, 1932;Northrop & Kunitz, 1932;Northrop, Kunitz & Herriott, 1948), the finding by Li (1948Li ( , 1949Li ( , 1950 and Cortis-Jones, Crooke, Henly, Morris & Morris (1950) that the activity of certain very highly purified pituitary hormones can be obtained in the form of quite small peptides, though it is uncertain if these were originally attached to the protein by conventional peptide bonds, means that the hypothesis of an active peptide grouping in insulin, attached to a larger protein mass, cannot yet be rejected. SUMMARY 1.…”