108 POISONOUS PKOTEINS 



protein poisons and the residues, all give the 

 biuret reaction. The residues will not give the 

 reaction in dilutions much greater than 1-100. 

 This indicates that the proteins and their split 

 products contain an acid amide group and other 

 substituted amide groups attached to neighbor- 

 ing carbon atoms, and that the end products 

 have not been deamidized in cleaving. 



2. Gies' biuret reagent gives similar results. 



3. The 'proteins and their split products all 

 give the xanthoproteic reaction, and the poi- 

 sons, in greater dilutions than the proteins or 

 the residues, indicating that they all contain 

 benzene nuclei and that in cleaving, these tend 

 to concentrate in the poison. 



4. The residues do not give Millon's reaction 

 and the poisons give it in greater dilutions than 

 the proteins, indicating that all the mono-hy- 

 droxy-benzene nuclei (tyrosine) are cleaved off 

 into the poison. It is interesting to note the 

 strong reaction given by the colon cell substance 

 and by the poison. 



5. The residues do not give Bardach's reac- 

 tion and all soluble proteins are said to give it. 

 The residues are alkaline and soluble. 



6. The poisons do not give the Molisch reac- 

 tion and the residues give a stronger Molisch 

 than the proteins, indicating that the carbohy- 



