CHEMICAL COMPOSITION OF PROTEIN MOLECULE 25 



DERIVATIVES OF PROTEINS. 



The result of hydrolysis definitely shows that the various proteins 

 are composed of the same units ; in some cases certain are missing, and 

 in other cases one or more units exceed the others by very large 

 amounts. 



The protamines are built up almost exclusively of diamino acids, 

 salmine containing over 80 per cent, of arginine. Only small amounts 

 of monoamino acids are present in them, and even these amounts may 

 be due to impurity, for fish sperm only at maturity is made up of 

 protamine and nucleic acid, whereas at other times histone takes the 

 place of protamine, and histones contain less diamino acids. Kossel 

 and Dakin's analysis appears to show us a quantitative result in the 

 case of salmine. 



The histones contain about 30 per cent, of diamino acids, and only 

 in the case of thymus-histone has an estimation been made of the 

 monoamino acids. They were supposed to be intermediate compounds 

 between protamines and other proteins, and this supposition is confirmed 

 by the results of analysis. 



The protein constituent globin of haemoglobin has always been 

 regarded as a histone, but the presence of only 20 per cent, of diamino 



