THE PROTEINS AND THEIR METABOLISM 



87 



2. Glutamic acid or a-ammo glutaric acid. 

 COOH 



Y-CH 2 



a-CHNH 



COOH 



These amino acids are strongly acid in reaction because of the fact 

 that they possess two acid radicals and only one base. In spite of the fact 

 that they are strongly acid, they possess the power of combining with other 

 acids, forming salts. 



COOH 



COOH 



CH 



COOH 

 Aspartic acid 



COOII 

 Aspartic acid 

 hydrochlorid 



They also have the power of combining with two alkali radicals be- 

 cause of the two carboxyl ( COOH) radicals. 



COOH 



I 

 CH 2 



| 

 CHNH 2 



I 

 COOH 



2NaOH 



COONa 



I 

 CH 2 



CHNH 2 



I 

 COONa 



2HO 



C. Hydroxy- and Thio-a-amino acids. 



1. Serin or a-amino fi-hydroxypropionic acid. 

 P-CH 2 OH 



COOH 



