THE CHEMICAL CONSTITUENTS OF PLANTS 209 



Diamino-monocarboxylic acids. 



12. Arginine = a-amino-8-guanidine valerianic acid, C,-H 14 N 4 O 2 , 



NH:C(NH : ,).NH.CH. 2 .CH 2 .CH 2 .CH(NH 2 ).COOH 



13. Lysine = a-e-diamino-caproic acid, C fl H u N 2 O 3f 



NH. 2 .CH 2 CH 2 .CH 2 .CH 2 .CH(NH 2 ).COOH 



14. Caseinic acid = diamino-trioxydodecanic acid, C 12 H 26 N 2 O 5 . 



15. Ornithine = a-S-amino-valerianic acid, C 5 H 12 N.,0 2 , 



NH 2 .CH 2 .CH 2 .CH 2 .CH(NH 2 ).COOH - 



Diamino-dicarboxylic acid. 



16. Cystine = dicysteine, = di (ft thio-a-amino-propionic acid), 



C G H 1 .,N 2 4 S 2 , 

 COOH.CH(NH 2 ).CH 2 .S - S.CH 2 .CH(NH 2 ).COOH 



Heterocyclic amino-carboxylic acids. 



li 



17. Histidine = a-amino-/3-iminazole propionic acid, C 6 H 9 N 3 O 2 , 



CH=C CH 2 .CH(NH 2 ).COOH 



NH 



v 



CH 



18. Proline = a-pyrrolidine carboxylic acid, C 5 H 9 NO,,, 



CH 2 CH 2 " 



CH CH.COOH 



"NH 



19. Oxyproline = hydroxy-pyrrolidine carboxylic acid, C 5 H 9 NO 3 



HOCH CH 



I I 



CH 2 CH.COOH 



^NH 



20. Tryptophane = /2-indole-a-amino -propionic acid, C 11 H 12 N 2 O., V , 



C CH 2 .CH(NH 2 ).COOH 



C 6 H 4 CH 



\/ 

 NH 



The methods used in the hydrolysis of proteins and in the identifi- 

 cation and determination of the products are too complex and 

 involved to permit of any description here. Much work on this 

 subject has been done recently, especially in Germany by Fischer, Ab- 

 derhalden, Kossel and others and in America by Osborne, Hart and 

 others. 



The results show that the various proteins are built up of very 

 varying proportions of the amino-acids. 



14 



