Action of Peptides in the Nutrition of Young Mice.

Abstract

It seems impossible to make young mice grow at a normal rate on any mixtures of known amino acids substituted for the protein of the diet, no matter what the proportion of the amino acids. By adding the vitamin B in the form of yeast slight growth is obtained, but by adding the vitamin B fraction in the form of the Osborne-Wakeman preparation there is usually a decline in weight. Since the active principle in the cure of pernicious anemia as well as insulin, secretin, and glutathione, are all said to be peptides, it seems probable that peptides are necessary in nutrition. The end products of both gastric and pancreatic digestion of proteins contain peptides, and it seems probable that they, to some extent, would be absorbed as such. If the stomach is removed from a mammal, death finally occurs accompanied by anemia. A dog may live for some months or a man for some years without a stomach but finally dies. A person with pernicious anemia has no gastric digestion and when fed the gastric digest of a protein is cured of the symptoms. It may take a long time to find just what peptides are necessary. So far the results are: Young mice fed on a mixture of the known amino acids, some radicals of prosthetic groups vitamines, mineral salts, carbohydrate, and fat, decline in weight and health. Control mice fed on this diet to which has been added all of the peptides which I have yet been able to obtain, decline at a less rapid rate, are more lively and apparently healthy, and live longer than those not receiving the peptides.

If casein is hydrolyzed with acid, there is a progressive hydrolysis of all imid linkages, accompanied by a slow destruction of the amino acids.