POLVPEPTIDES 73 



days in a developing chick and in pig embryos when they were 3-3 cm. 

 long, but not 3*2 cm. long (about thirty-seven days old). The kidneys 

 and liver contained most of the active enzyme. On account of the 

 wide distribution of the proteoclastic enzymes in tissues no perfect 

 localisation was found possible. 



Even simpler than the polypeptides containing tyrosine for detecting 

 enzymes are polypeptides containing tryptophane. These compounds 

 do not react with bromine water, but when hydrolysed the tryptophane 

 is easily recognised by this colour reaction. These polypeptides are 

 not so useful for animal as for vegetable tissues ; animal tissues usually 

 give rise to some tryptophane by autolysis and no conclusive result is 

 obtained unless very careful controls are also made. 



The use of these polypeptides was suggested by Neubauer and 

 Fischer in 1909 and they used glycyl-1-tryptophane l to detect ferments 

 in certain pathological conditions. 



Walker Hall and Williamson have found that the gastric contents 

 of a case of cancer of the stomach, the cerebro-spinal fluid in a case of 

 meningitis, and pleuritic exudate hydrolysed glycyl-1-tryptophane. The 

 presence of an enzyme which hydrolyses these polypeptides is, accord- 

 ing to Kuttner and Pulvermacher, not a specific test for cancer of the 

 stomach. Koelker mentions that the enzyme probably comes from the 

 saliva ; normally it is destroyed by acid in the stomach but owing to 

 the absence of acid in certain cases its activity may be the cause of 

 positive results. 



Abderhalden has tested glycyl-1-tryptophane, 1-tryptophyl-glycine, 

 d-alanyl-tryptophane, 1-leucyl-l-tryptophane, 1-leucyl-glycyl-l-trypto- 

 phane and 1-tryptophyl-glutamic acid with pancreas extract, yeast juice 

 and other enzyme solutions. All were hydrolysed. 



Glycyl-1-tryptophane was used by Jacoby to detect enzymes in the 

 fertilised and developing eggs of Arbacia ; by Koblanck and Lob in 

 the ovaries of the rabbit and pig. 



This test may also be carried out with slices of the organs : they are 

 placed in a I per cent, solution of the dipeptide, removed after 

 twelve to forty-eight hours and the solution is tested for tryptophane 

 by the bromine water reaction. 



Solutions of the optically active polypeptides can be employed 

 with more certainty. It simply suffices to place the polypeptide and 

 enzyme solutions in a polarimeter tube and observe the change in rota- 



1 Kalle & Co. in Biebrich supply this compound under the term " ferment diagnostikon ". 



