PROTEINS 



109 



Table S-2 — (Continued) 



Foodstuff 

 Peas . . . 



Rice 



Rye 



Wheat 



Percen tage in 



foodstuff 



2.0 



10.0 



1.0 

 11.5 



24.5 



4.0 

 5.9 



9.9 . 



4.0 

 2.44 



1.76 



0.43 



8.63 



3.91 

 4.17 

 0.63 

 0.36 

 0.43 

 1.10 



Total 



10.60 



of clothing are protein in character. Probably all enzymes and some 

 hormones are proteins. The discovery of the existence of proteins as 

 viruses, toxins, and poisons, deadly to man, has emphasized their vital 

 importance and greatly increased the impetus to research. 



Elementary composition 



All proteins contain carbon, hydrogen, oxygen, and nitrogen. Most 

 proteins contain sulfur, some contain phosphorus, and a few contain iroij, 

 copper, or manganese. Phosphorus is not really a constituent of the 

 protein part of the molecule. Only the conjugated proteins — proteins 

 united with a prosthetic (additional) group — contain phosphorus, the 

 phosphorus being in the form of a phosphoric acid ester. Iron, likewise, 

 is not found in any amino acid. Hence it is not in the protein molecule 

 proper but is contained in the prosthetic group, e.g., hematin in hemo- 

 globin. 



