An attempt to discover the cause of the specific dynamic action of protein

Abstract

The writer has shown that if glutamic acid be given to a phlorhizined dog three of its carbon atoms are converted into glucose. One can write the reaction thus:

2HOOC · CH₂ · CH₂ · CHNH₂ · COOH + 2HOH = 2CH₃ COOH + C₆H₁₂O₆ + 2NH₃.

Rubner sought to explain the increase in heat production which followed meat ingestion—its specific dynamic action—by the supposition that protein could be used for the vital activities of the cells only in so far as it was converted into dextrose; all the oxidations of other portions of the protein yielded free heat within the organism which could not be used as power for the living mechanism. If this were true then a considerable increase in the output of carbon dioxide would follow the administration of glutamic acid superimposed upon a regular standard diet. Alanin, which Ringer and the writer have shown to be completely convertible into dextrose, should show no specific dynamic action, whereas tyrosin with its many cleavages before it reaches a stage for use in metabolism might show a pronounced increase in carbon dioxide output.