iv PHYSIOLOGY OF CARBOHYDRATE RADICALS 165 



to the hydrochloride of a-/?-di-amino-propionic acid 1 and obtained 

 iso-serin or a-oxy-/?-amino-propionic acid. 



CH 2 (NH 2 ) . CH(NH 2 )COOH -> CH 2 (NH 2 ) . CH(OH) . COOH. 



" In this nitrite reaction, as in the physiological des-amination of the 

 di-amino-fatty-acids, the amino-group, NH 2 , next the carboxyl-group 

 (COOH) is more readily eliminated," for S-amino-valerianic acid is 

 formed during putrefaction out of the a-S-di-amino-valerianic acid, or 

 out of arginin, as shown by E. and H. Salkowski. 2 



Paul Mayer, 3 by injecting the hydrochloride of di-amino-propionic 

 acid into rabbits, found this di-amino acid to become des-aminated : 



CH 2 . NH 2 CH 2 . OH 



I I 



CH . NH 2 + 2H 2 = CH . OH + 2NH 3 



COOH COOH. 



Di-amino-propionic acid+ water = glyceric acid + ammonia. 



This transformation into glyceric acid is a new proof of the intimate 

 physiological relationship between amino- compounds and hydroxyl- 

 com pounds, and between the latter and carbohydrates, because by the 

 reduction of glyceric acid, CH 2 OH CHOH COOH, into glycerine- 

 aldehyde, CH 2 OH CHOH COH, there is formed a true sugar. 

 The glycerine-aldehyde being in itself a true sugar, by condensation of 

 two molecules can readily give rise to hexoses, according to Wohl and 

 Neuberg, 4 analogous to the two-carbon series, when, as Mayer 5 has 

 shown, there is formed glycol-aldehyde. 



The probable inter -relationship between e?-glycuronic acid and 

 d-g\y eerie acid has already been alluded to on p. 36 under the 

 di-amino-propionic acid. 



As in the fatty di-amino-acids the a-NH 2 -radical is eliminated by 

 the action of nitrites, 



lysin, NH 2 . CH 2 . [CH 2 ] 3 CH . NH 2 . COOH, 

 probably gives rise to e-amino-a-oxy-caproic acid : 



NH 2 . CH 2 [CH 2 ] 3 CH(OH) . COOH, 



1 They now advise the use of barium nitrite. Ber. d. deutsch. chem. Ges. 36. 4384 

 (1903). 



2 E. and H. Salkowski, ibid. 16. 1191 and 1802 (1883). 



3 P. Mayer, Zdtschr. f. physiol. Chem. 42. 59 (1904). 



4 Wohl and Neuberg, Ber. d. deutsch. chem. Ges. 33. 3095 (1900). 



5 P. Mayer, Zdtschr. f. physiol. Chem. 38. 135 (1903). 



