AMIXO-ACIDS. 45 



This has the constitution 



NH 2 



G. Hydroxy-diamino-mono-carboxylic acid. 

 Tri-hydroxy-diamino-dodecanoic acid . 



H. Diamino-di-carboxylic acids. 

 Diamino-glutaric acid. 

 Diamino-adipic acid. 



I. Hydroxy-diamino-di-carboxylic acids. 

 Hydroxy-diamino-sebacic acid. 

 Dihydroxy-diamino-suberic acid, and probably others. 



J. Pyrrolidine compounds. 



a-pyrrolidine-carboxylic acid, or proline. 

 Oxy-pyrrolidine-carboxylic acid, or oxy-proline. 



Proline has the constitution 

 CH, CH, 



CH 2 



CH COOH 



V 



NH 



K. Thio-amino-acids. 



Protein-cystine and stone -cystine. 



These are derived respectively from 



a-amino-/?-thio-lactic acid, and 



a-thio-/?-amino-lactic acid, and are represented by the following 

 constitutions : 



Among other compounds obtained by the hydrolysis of proteins are : 

 L. Purine bases. These are contained in the nucleo -proteins ; they are 



products containing a pyrimidine and a glyoxaline (or imidazolyl) ring, 



thus 



Pyrimidine. Glyoxaline. Purine. 



J N = 4 CH IN = 6 CH 



2 CH 5 CH CH NH^ 2 CH 5 C ^K 



II II II x>CH || |i >CH 



3 N 6 CH CH- N : 3 N _4 C _ N 9 / 



