PRODUCTS OF HYDROLYSIS 55 



B. Hydrolysis by Alkalies. 



Alkalies have been frequently used to effect hydrolytic decomposi- 

 tion of proteins, notably by Schutzenberger and Emil Fischer, but in 

 comparison with acids they have been little used, for some of the 

 amino-acids, notably arginine and cystine, are destroyed by heating 

 with them. Osborne, Leavenworth and Brautlecht (364) found that 

 continued boiling with a strong solution of sodium hydroxide yields a 

 quantity of ammonia corresponding to the sum of the amide nitrogen 

 and one-half of the nitrogen of the arginine. With these exceptions 

 the primary products of alkaline hydrolysis are, so far as is now known, 

 the same as those produced by acids. In regard to the proportion of 

 ammonia eliminated by alkaline hydrolysis, and the forms of union of 

 nitrogen in the molecule of some vegetable proteins, the reader is re- 

 ferred to page 62. 



C. Colour Reactions. 



From what has just been said of the products of protein decom- 

 position it is evident that the colour reactions of the vegetable proteins 

 are practically the same as those of the animal proteins. None of 

 these reactions, therefore, deserves special consideration except those 

 showing the presence of carbohydrates. In the case of vegetable 

 proteins, associated so intimately with a variety of carbohydrates, 

 Molisch's reaction is of especial interest, for this indicates the presence 

 of even minute quantities of carbohydrates. Preparations of proteins 

 which do not give this reaction are entirely free from any carbohydrate 

 or from any substance which can yield a carbohydrate or furfurol, as, 

 for instance, glucosides or nucleic acid. The fact that a large number 

 of the vegetable proteins give absolutely no trace of colour with 

 Molisch's test, shows that a carbohydrate complex is not a constituent 

 of the molecules of a large number of vegetable proteins. Whether 

 protein preparations which give Molisch's reaction contain a carbohy- 

 drate group as a constituent of their molecules, or as a constituent of 

 some group organically united with the protein molecule, or as simply 

 a contamination, cannot yet be definitely decided. Attempts to isolate 

 a carbohydrate from such proteins have, up to the present time, failed, 

 and we have no good ground to believe that any of the seed proteins 

 actually contain a carbohydrate group as a constituent of their mole- 

 cules. On the other hand, we have no conclusive evidence that some 

 of them do not contain such a group, for it is extremely difficult to iso- 

 late carbohydrate from a mixture of protein decomposition products, and 



