l6o PHYSIOLOGY OF NUTRITION 



d-Valin (a-amino-iso valeric acid), „ 3 />CHCHNH 2 COOH. 



/-Leucin (a-amino-isocaproic acid, a-amino-isobutyl-acetic acid), 



^ aN ^CHCH 2 CHNH 2 COOH. 

 CH3/ 



d-Isoleucin (/3-methyl-/3-ethyl-a:-ammo-propionic acid), 



i^'N CHCHNH 2 COOH. 

 C2XI5/ 



/-Aspartic acid (a-amino-succinic acid), COOHCH 2 CHNH 2 COOH. 



^-Glutamic acid (a-amino-glutaric acid), COOHCH 2 CH 2 CHNH 2 COOH. 



B. Diamino acids 



Lysin (a-e-diamino-caproicacid), NH 2 CH 2 CH 2 CH 2 CH 2 CHNH 2 COOH. 



J-arginin (5-guanidin-a-amino- valeric aci),d 



HN - c/ NH2 



N ' ' \NHCH 2 CH 2 CH 2 CHNH 2 COOH. 



Cystin (a-diamino-/3-dithio-dilactylic acid), 



CH 2 CHNH 2 COOH— S— S— CH 2 CHNH 2 COOH. 



Aromatic Compounds 



/-Phenyl alanin ((3-phenyl-a-amino-propionic acid), 



C 6 H 5 CH 2 CHNH 2 COOH. 



/-Tyrosin (/3-para-hydroxyphenyl-a-amino-propionic acid), 



HOC 6 H 4 CH 2 CHNH 2 COOH. 



Heterocyclic Compounds, Derivatives of Imidazol, Pyrrol and Indol 



/-Histidin (/3-imidazol-a-amino-propionic acid), 

 CH = C— CH 2 CHNH 2 COOH 



N NH 



V 



CH 



/-Prolin (a-pyrrolidin-carboxylic acid), 

 CH 2 — CH 2 



CH 2 CHCOOH 



NH 



/-Hydroxyprolin (hydroxy -a-pyrrolidin-carboxylic acid) , 

 /-Tryptophan (/3-indol-a-amino-propionic acid). 

 C— CH 2 CHNH 2 COOH 



CeH^v /CH 



NH 



The relative amounts of the various amino acids obtained from different 

 proteins are not constant, as is evident from the following table, which shows 

 these amounts for seeds of wheat and oats. 



