52 THE CHEMICAL CONSTITUTION OF THE PROTEINS 

 Derivatives of Proteins. 



Complete analyses of the proteoses products intermediate between 

 the proteins and amino acids are being undertaken by Levene in con- 

 junction with Van Slyke and Birchard. The qualitative differences ob- 

 served by the older workers, Kuhne, Chittenden, Neumeister and the 

 analytical differences observed by Pick have not been found. The 

 generally accepted view that heteroalbumose contains more hexone bases 

 than protoalbumose is not confirmed. We may note that heteroal- 

 bumose contains more glutamic acid than protoalbumose, and that it 

 contains I per cent, more histidine. Skraup and his pupils have made 

 numerous analyses of various intermediate products, all of which seem to 

 contain most of the units. There are differences in the actual amounts but 

 they are insignificant. The examination of the substances termed 

 kyrines by Siegfried leads him to regard them as mixtures. Dennstedt 

 and Hassler believe that in the formation of proteoses the process of 

 oxidation occurs at the same time as hydrolysis. 



The analysis of plastein also does not answer the much discussed 

 question whether it represents a synthetical product or a further pro- 

 duct of digestion. The figures so nearly resemble those for Witte's 

 peptone that one would be inclined to the view that plastein is still a 

 mixture, which is precipitated under the conditions of the experiment. 



The analyses of the proteoses show that they contain all the amino 

 acids originally present in the protein ; if a splitting of the large mole- 

 cule had occurred in such a way that four or five amino acids only were 

 present in each product, the synthetical problem would be easier ; we 

 have still no substantial clue as to the order in which the units are 

 combined in the molecule (see Part II.). 



