Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/77

 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 decomposites are given.



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 0°, as the resulting dipeptide glycyl-glycin is optically inactive (see p. 53 (2)).