Beiträge zur Chemie des Insulins. 5. Mitteilung über Insulin.

Abstract

High grade amorphous insulin preparations as well as crystalline insulin are coagulated in hot dilute HC1 solution without appreciable loss of potency. This product and crystalline insulin in distinction from other insulins do not split off CH3 groups. Insulin inactivated by formaldehyde with loss of potency may be in part reactivated by liberation of HCHO. Inactivation of insulin with alkali results in a concomitant loss of ammonia or other amine with a profound change in optical activity. On the basis of the ammonia liberation, a minimum molecular weight of 8000 is indicated. The active group represents a small fraction of the protein molecule, with a high specific optical rotation. Absorption bands of insulin in the ultra violet and x-ray pictures of the crystals are discussed.