ORIGIN OF SUGAR FROM AMINOACIDS 239 



those of Eohmann, E. Cohn, Nebelthau, Neuberg and Lang- 

 stein, Knopf, Halsey, F. Kraus, Embden and Salomon, 

 Glassner and E. Pick and Graham Lusk) 51 have led to the 

 conclusion that sugar production from aminoacids, at least 

 from glycocoll, alanin, asparaginic acid and glutaminic acid, 

 cannot well be doubted. The conceptions framed to explain 

 the process are entirely hypothetical. The synthesis of 

 sugar may possibly take place through the formation of sub- 

 stances containing one, two or three carbon atoms, as 

 formaldehyde, glycolaldehyde and lactic acid, the fitness of 

 which for taking part in direct construction of sugar is more 

 or less to be expected. The author personally is more 

 sympathetically attracted to such a conception as that which 

 supposes leucin to be decomposed into two triple-carbon 

 compounds 52 to be synthesized into sugar, than to any idea 

 of a "stretching" of the branched 



LEUCIN LACTIC ACID GLUCOSE 



CH 3 .CH, 



VH CH, 



in, > 2CH.OH > CeH 12 6 



CH.NH 2 COOH 



COOH 



six-carbon chain of leucin to bring about its transformation 

 into sugar. 



Einger and Graham Lusk 53 by the employment of an 

 excellently adapted method succeeded in producing in dogs 

 a very uniform glycosuria ; and, after the D | N ratio in the 

 urine had become constant, fed aminoacids to the animals. 

 By measuring the resultant increases of sugar excretion 

 they concluded that glycocoll and alanin can be all utilized in 

 formation of sugar, but of the four carbon atoms of 



01 Literature : J. Wohlgemuth, Handb. d. Biochem., 3', 165-166, 1910. 



62 Cf. L. Langstein, Ergebn. d. Physiol., 3', 473, 1904. 



53 A. J. Ringer and Graham Lusk (Cornell Univ., New York), Zeitschr. f. 

 physiol. Chem., 66, 106, 1910; Jour. Amer. Chem. Soc., 82, 671, 1910; cited in 

 Centralbl. f. d. ges. Biol., 10, No. 2348. 



