48 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



taining more leucine and less glutamic acid. Hordein contains more 

 proline than any other protein. Wheat-glutenin and the other 

 glutelins seem to contain all the amino acids which have been isolated. 

 The analysis of rice by the Japanese workers is for the whole grain 

 and not for the isolated protein ; they found that the husk of the grain 

 also contained protein, and that the proportions of the constituent 

 amino acids were different. 



Phosphoproteins. 



There is no striking peculiarity noticeable in the analyses of the 

 phosphoproteins. If we disregard the small quantity of glycine found 

 in vitellin by Abderhalden and Hunter who used the commercial 

 product in their investigation we must note the absence of this amino 

 acid in the phosphoproteins. Apparently, from the results obtained 

 by numerous workers, glycine is the only amino acid which can be 

 synthesised by the animal body from other products ; if these phospho- 

 proteins, especially vitellin, really contain no glycine a further proof 

 is given of its synthesis by animals. Abderhalden and Kempe in their 

 experiments on the synthesis of amino acids in the chick could not 

 detect any differences in the amounts of glycine, tyrosine, and glutamic 

 acid at different periods of development. 



The analysis of caseinogen by Osborne and Guest is the most 

 recent, and the data given are the highest which have been observed 

 by them and other workers. On account of the importance of this 

 protein in nutrition it is very necessary to have as thorough an analysis 

 as possible. The latest analysis has increased our knowledge of the 

 constituent amino acids by about 1 5 per cent. Some 30 per cent, of 

 the protein still remains unaccounted for. 



The caseinogens of cow's, goat's, and human milk appear to have 

 the same composition. 



Vitellin, which has been analysed by four sets of investigators, has 

 given very different results. The values of Hugounenq and of Levene 

 and Alsberg do not correspond with the values of Abderhalden and 

 Hunter or of Osborne and Jones. The values by the latter workers 

 are the most recent >and are probably the most accurate. The 

 phosphoproteins in the eggs of fish (ichthulin) and the frog have 

 also been analysed by Hugounenq and his assistants. 



