THE PROTEINS AND THEIR METABOLISM 



89 



2. Ornithin or a-arnino 6-amino valerianic acid. 

 5-CH 2 NH 2 



Y-CH 2 



a-CHNH 2 



COOH 



3. Arginin or a-amino 5-guanidin valerianic acid. 



C 





Y-CH 



I 

 P-CH 



<x-CHNH 



COOH 



These substances are strongly alkaline in reaction. The last substance, 

 on hydrolysis with alkali or an enzyme known as arginase, splits into urea 

 and ornithin. This latter substance is not found as such among the pro- 

 tein cleavage products. 



E. Aromatic amino acids. 



1. Phenyl-alanin or a-amino /3-phenyl propionic acid. 

 CH 



/ \ 

 HC CH 



|| {-Phenyl radical 

 HC CH 



\ / - 

 C 



CH 2 

 CKN T H 2 1 

 COOH 



Alanin radical 



