52 METHODS FOR THE STUDY OF FERMENTS 



information on the power of rotation of three poly- 

 peptides composed of three amino-acids. At the same 

 time the optical relations of the individual decom- 

 posites are given. 



(l) +20 (2) - 64 



1-Leucyl-glycyl-d-alanin Glycyl-d-alanyl-glycin 



(3) 



d-Alanyl-glycyl-glycin 



50 



The explanation of our example (3) illustrates the 

 others as well. The tripeptide d-alanyl-glycyl-glycin 

 rotates + 30. If glycin (==glycocoll) were first split 

 off by a ferment, then the dipeptide d-alanyl- 

 glycin (see p. 53 (i)) would appear. The rotation 

 of the solution would rise towards the right, 

 because d-alanyl-glycin turns further to the right 

 than the original material. If, on the contrary, 

 d-alanin were set free first, then the rotation would 

 soon decrease to o, as the resulting dipeptide glycyl- 

 glycin is optically inactive (see p. 53 (2)). 



with the chemistry of albumen, with studies in immunity, with 

 bacteriology, and so on, but which fails simply through lack of 

 means for the upkeep of a small army of capable young 

 chemists. 



