ALBUMINS OR PROTEINS. 185 



tioned, the ferment will attack only that specific combination which con- 

 tains the corresponding optically active amino acid in the albumin. As 

 d-alanine and /-leucine are formed by the hydrolysis of albumin, the racemic 

 compound necessarily contains the combination, d-alanyl-/-leucine. There- 

 fore the partially hydrolysed racemic body, obtained by fermentation is 

 d-alanyl-Z-leucine + Z-alanyl-d-leucine. The unchanged portion must be 

 d-alanyl-d-leucine + /-alanyl-Weucine. 



We have intentionally taken this example in order to show the selective 

 action of trypsin on the large number of polypeptides, on the one hand, 

 and, on the other, to illustrate the fact that the different behavior of the fer- 

 ments towards various racemic compounds can be utilized in determining 

 the configuration of the substance in question. 



The results obtained by fermentation only become conclusive after all 

 of the different racemic compounds have been subjected to the treatment. 

 We can only then decide whether or not a definite compound is attacked 

 by trypsin. The relations become much more simple when the active 

 peptides are subjected to investigation. Even then, however, if a certain 

 combination of amino acids is not hydrolyzed by trypsin, it does not by any 

 means follow necessarily that such a combination is not present in albumin. 

 We have already seen that in the breaking down of the different proteins by 

 trypsin, different amounts of residues remain which resist digestion strongly. 

 The albumin molecule evidently contains chains which are not broken 

 by trypsin. 



We already know, and shall later discuss the subject more in detail, 1 

 that the ferments, as a rule, work in a specific manner, and are very strongly 

 influenced by differences of configuration. The fact that trypsin splits 

 the synthetic polypeptides is a strong indication for the assumption that 

 such anhydride-linked amino acid chains are present in albumin. 



Another important proof, that completely agrees with Emil Fischer's 

 assumptions, is obtained by a study of the behavior of the polypeptides in 

 the animal organism. They are decomposed in the same manner as pro- 

 teins, even when injected subcutaneously. Glycyl-glycine is hydrolyzed. 

 A small part of it appears in the urine as glycocoll. 2 Dialanyl-cystine and 

 clileucyl-cystine are similarly acted upon, and the cystine is consumed in the 

 same manner as if it were introduced as such into the animal organism. 

 Glycyl-Z-tyrosin is likewise completely consumed. 3 Finally, it has been 

 definitely proved for glycyl-glycine, tri-glycine, and alanyl-alanine, 4 that 

 the decomposition of these peptides proceeds in the same manner as if the 

 individual components alone had been introduced. 



1 E. Abderhalden and P. Bergell: Z. physiol. Chem. 39, 9 (1903). 



2 E. Abderhalden and F. Samuely: ibid. 46, 187 (1905). 



3 E. Abderhalden and P. Rona: ibid. 46, 176 (1905). 



4 E. Abderhalden and Y. Teruuchi: ibid. 47, 159 (1906). 



