238 FORMATION OF SUGAR FROM PROTEIN 



confirmed, 46 and that Weinland 's work, 47 to the author's 

 mind, should be repeated by a number of different methods 

 before final credence can be given it. 48 



Formation of Sugar from Various Proteins. Consider- 

 able work has been expended upon the question of the rela- 

 tion of various proteins to the amount of sugar which they 

 are capable of producing in metabolism, but with little other 

 result, as far as the writer can observe, than the fact that 

 the quantity of carbohydrate preformed in the proteid sub- 

 stances (glucosamine) is by no means striking. Quite re- 

 cently experiments have been repeated in M. Cramer's 

 laboratory showing in comparative feeding tests on a phlor- 

 idzin dog with meat and casein (casein is a carbohydrate- 

 free protein) a difference in favor of casein. 49 The amounts 

 of sugar which can be produced from protein (based on 

 calculation of the D|N relation) have been given in highly 

 varying proportion ; incidentally it was calculated that after 

 feeding meat half of the energy of the protein can take on 

 the form of sugar and can be stored as glycogen for future 

 use. Such statements cannot, however, as yet be regarded as 

 final. 50 



Origin of Sugar from Aminoacids. Having clearly be- 

 fore us the facts of sugar formation from protein, we may 

 proceed to the question of the chemistry of this process. 



Explanation of the mechanism of sugar production from 

 protein has been sought by administering the individual 

 "building stones " of protein, the aminoacids, to dogs with 

 pancreatic diabetes and phloridzin diabetes, and determin- 

 ing their influence upon sugar elimination and glycogen 

 formation. Investigations with this in view (particularly 



46 Cf. L. Langstein, Ergebn. d. Physiol., 1', 108, 1902. 



* 7 E. Weinland, Zeitschr. f. Biol., 49, 421-466, 1907. 



*" O. Krummacher and E. Weinland, Zeitschr. f. Biol., 52, 273, 1909. 



49 P. Rohmer (M. Cremer's Lab.), Zeitschr. f. Biol., 54, 455, 1911. 



50 Investigations by Kiilz, Lusk, Halsey, Liithje, Bendix, Berger, Lehmann, 

 Schumann-Leclerc, Mohr, Falta, Therman, G. Miiller and others. Literature: 

 P. Rohmer, 1. c. 



