Nutrition 



119 



CH-N 



CH2 — S — CH3 



I 

 CH2 



I 

 CH-NH2 



COOH 

 methionine 



\ 



,CH 



C-NH 



I 

 CH2 



CH-NH2 



COOH 

 histidine 



The amino acids synthesized by growing rats from carbohydrate and am- 

 monia-yielding compounds such as other amino acids are: 



Those which are synthesized from specific amino acids are: 



OH 



CH2-S-S-CH2 



CH-NH2 CH-NHo 



I I 



COOH COOH 



cystine (from methionine) 



/ 



HC "CH 



HC CH 



\ / 

 C 



I 

 CH2 



I 

 CH-NH2 



I 

 COOH 



tyrosine (from phenylalanine) 



The interactions among amino acids are important, and reported inhibition 

 of growth by certain amino acids is probably really due to lack of balance 

 among antagonists. An amino acid which is synthesized from another one 



