40 THE CHEMICAL CONSTITUTION OF THE PROTEINS 



THE RESULTS OF THE ANALYSIS. 



Inspection of the results of analysis, which are tabulated on pages 

 53-62, shows that there is a considerable deficit in the sum of the 

 amino acids composing the protein molecule. 



The best analyses are those of the protamines, of the silk-fibroin of 

 spider's silk, arid the gliadin of wheat ; in these some 80-90 per cent, 

 of the protein is accounted for ; in most cases the sum of the figures 

 only reaches 50-70 per cent, and in the other cases complete analyses 

 do not exist. The deficiencies are due almost entirely to losses incurred 

 in isolating and purifying the amino acids rather than to the presence 

 of new units, for no new constituent of the protein molecule has been 

 noted since 1904, when Fischer described diaminotrioxydodecanic 

 acid; this compound has not been found in any other protein than 

 caseinogen, and Osborne with his collaborators in spite of a very care- 

 ful analysis of this substance failed to find it. 



A careful inquiry where the loss occurs has been made by Osborne 

 in conjunction with Leavenworth and Brautlecht and with Jones, and 

 by Abderhalden, who estimates the nitrogen at each stage in the pro- 

 cess for isolating the monoamino acids. 



Osborne, Leavenworth and Brautlecht have proved that the loss 

 does not fall upon the diamino acids. They are convinced that the 

 Kossel, Kutscher, Patten, Steudel, and Weiss method is extremely satis- 

 factory, for they have been able to recover from 80-90 per cent, of the 

 diamino acids in a pure state. They consider that no other diamino 

 acid than the three hexone bases is present in most proteins ; Fischer 

 and Abderhalden's diaminotrioxydodecanic acid in caseinogen may be 

 an exception ; this protein seems to be the most complex in the number 

 of units which it contains. 



The loss therefore occurs in the isolation and estimation of the 

 monoamino acids. Fischer pointed out, when he first described his 

 ester method, that the values were not to be regarded as quantitative. 

 The fact that all the figures given are those of the amount of the pure 

 dry compound isolated is sufficient evidence that the total quantity of 

 products is not accounted for. 



The sources of loss in the several steps of the long process have re- 



