The physiology of the amino acids / by Frank P. Underhill.

  • Underhill, Frank P. (Frank Pell), 1877-1932.
Date:
1915
Catalogue details

Licence: In copyright

Credit: The physiology of the amino acids / by Frank P. Underhill. Source: Wellcome Collection.

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    sugar production. If we take a typical protein as egg albumin, and then on the assumption that all the nitro- gen present is eliminated from the body as urea, we find left over a large carbon residue, the so-called “carbon moiety/’ of the protein which may be regarded as material capable of being transformed into carbo- hydrate. This potential of carbohydrate forming material must gain access to the blood stream, hence to the tissues, in the form of amino acids, in accord- ance with the present-day view of the processes of metabolism. The problem under consideration, there- fore, resolves itself in the question, “Are amino acids capable of being transformed into carbohydrates ?” The most convincing work in this direction is that of Lusk and his pupils. They have administered to dogs rendered diabetic with phlorhizin various amino acids and have observed that some yield sugar whereas others fail to do so. In their experiments the relation- ship between the dextrose and nitrogen of the urine, the D: N ratio, was determined. Under suitable con- ditions this becomes a constant. The ingestion of sugar forming substances changes this constant and any change serves as an index to the quantity of sugar formed from a given amount of substance introduced. It was found that the N-free parts of glycocoll, alanine, aspartic acid, and glutamic acid, containing respectively two, three, four, and five carbon atoms may be either completely or partially transformed to dextrose. All of the glycocoll and all of the alanine were converted