160 INTERMEDIATE METABOLISM 



Arginine (containing the guanidine group) 



NH=C 



\ 





NH, 



NH = C— NH— CH2CH2CIT2CHNH2COOH 



II. Amino-acids containing a Closed Chain. 

 Phenyl alanine 



CH2CHNH2COOH 



Tyrosine (oxyphenyl alanine) 



CH2CHNH2COOH 



OH 



Tryptophane (/J-indol alanine) 

 CH 



CHf \^^— CCH2CHNH2COOH 



CH 



G 

 CH NH 



CH 



Histidine (/S-imidazol alanine) 



CH 



/\ 

 NH N 



CH= C— CH,CHNH,COOH 



