FURTHER FATE OF AMINO ACIDS 109 



THE RELATIONSHIP BETWEEN CARBOHYDRATES AND 

 AMINO ACIDS 



i. The Formation of Carbohydrate from Amino Acids 



For a long time it has been accepted that carbo- 

 hydrate may be formed from ingested protein. To 

 determine the mechanism of this transformation many 

 experiments have been carried through upon animals. 

 In particular the formation of glycogen from ingested 

 protein has been subjected to experimentation and 

 although the consensus of opinion would indicate that 

 protein may give rise to glycogen formation, the 

 experimental conditions under which most of the inves- 

 tigations were made are not free from criticism. The 

 evidence of clinical experience, with diabetes, where 

 fat or carbohydrate ingestion cannot always be held 

 responsible for the large amounts of sugar passing 

 through the kidneys daily, points positively to protein 

 as the source of the carbohydrate excreted. In agree- 

 ment with this conception is the observation that the 

 urinary nitrogen and sugar excretion in the patho- 

 logical state mentioned run along parallel lines. 



How may this sugar formation be explained? One 

 may assume for instance, that protein contains groups 

 of a carbohydrate nature or groups closely allied to the 

 carbohydrates. Although it must be accepted that 

 certain proteins do contain carbohydrate groups, the 

 possession of such groups by proteins is by no means 

 universal, and, on the other hand, one is unwarranted 

 in stating that any specific protein will not lead to 



