iv PHYSIOLOGY OF CARBOHYDRATE RADICALS 167 



Serin by Fischer and Leuchs, 1 and Erlenmeyer ; 2 oxy-amino-succinic 

 acid by Neuberg and Silbermann ; 3 diamino-succinic acid by Tafel ; 4 

 diamino-adipic acid by Traube 5 and Kohl ; 6 diamino-suberic and 

 diamino-sebacic acids and their oxy-acids by Neuberg, 7 who has also 

 proved experimentally that the diamino-acids by splitting off CO 2 

 become converted into the diamines met with during digestion, 8 and 

 the ptomains 9 formed during putrefaction. 



The transformation of grape-sugar into methyl-imido-azol is 

 remarkable for the ease with which it occurs at the ordinary tempera- 

 ture, and also because the imido-azol forms the link between grape- 

 sugar on the one hand, and histidin on the other hand, for it has been 

 pointed out on p. 43 that histidin is an imido-azol compound. The 

 (a- or {}-) methyl-imido-azol (or methyl-glyoxalin) 



CH 3 C NH 



II 



CH 



is obtained by letting a solution of zinc hydroxide in ammonia act 

 on grape-sugar for six weeks. 



The intermediate stages from grape-sugar to lactic acid are 

 glyceric-aldehyde ^ methyl-glyoxal ^ lactic acid, and similarly 

 methyl-glyoxal is formed as an intermediate product during the 

 formation of methyl-imido-azol 



CH 2 (OH)[CH(OH)] 4 CHO -> CH 2 (OH) . CH(OH) . CHO * 



grape-sugar. glyceric-aldehyde. 



CH 3 .CO.CHO > CH 3 .CH(OH).COOH 



methyl-glyoxal. lactic acid. 



CH 3 CO H 3 N H CH.C NH 



COH H 3 N CK CH 



methyl-glyoxal + ammonia + formaldehyde. methylimido-azol. 



If the formaldehyde is a primary dissociation-product, and is not 

 formed secondarily from methyl-glyoxal, we are dealing here with 



1 E. Fischer and Leuchs, Ber. d. deutsch. chem. Ges. 35. 3790 (1902). 



2 E. Erlenmeyer, jun., ibid. 35. 3769 (1902) ; and Ann. d. Chem. 337, 236 (1904). 

 C. Neuberg and M. Silbermann, Zeitschr. f. physiol. Chem. 44. 147 (1905). 

 Tafel, Ber. d. deutsch. chem. Ges. 20. 244 (1887) ; and 26. 1890 (1893). 



W. Traube, ibid. 35. 4121 (1902). 



W. Kohl, ibid. 36. 172 (1903). 



C. Neuberg, Zeitschr. f. physiol. Chem. 45. 92 (1905) ; and ibid. p. 110. 



8 A. Loewy and C.' Neuberg, ibid. 43. 338 (1904). 



9 A. Ellinger, ibid. 29. 334 (1900) ; and Ber. d. deutsch. chem. Ges. 31. 3183 

 (1899). 



