CHAPTER IX. 



PRODUCTS OF HYDROLYSIS OF VEGETABLE PROTEINS. 

 A. Hydrolysis by Acids. 



SEED proteins are decomposed by heating with acids or by the action 

 of enzymes, and yield products of the same general character as those 

 obtained from proteins from animal sources. The experiments of 

 Chittenden (68) and his associates have shown that proteoses and pep- 

 tones of the same general character as those obtained from animal 

 proteins are formed from vegetable proteins by the action of pepsin 

 hydrochloric acid. 



Underhill (548) has shown that both the natural and artificial 

 proteoses of vegetable origin have the same physiological effect when 

 injected into the circulation of animals as have those of animal origin, 

 namely, a lowering of the blood pressure; rendering the blood uncoagu- 

 lable, accelerating the flow of lymph, deep narcosis, and other toxic 

 symptoms. 



Fisher and Abderhalden (in) obtained by tryptic digestion of 

 edestin a resistant product which contained all of the glycocoll, proline 

 and phenylalanine together with other amino-acids, and (i 12) from the 

 products of acid hydrolysis of gliadin a dipeptide of leucine and 

 glutaminic acid. Osborne and Clapp (339) similarly isolated a dipep- 

 tide of proline and phenylalanine from this latter protein after prolonged 

 hydrolysis with sulphuric acid. 



Whether the vegetable proteins are in general more difficult to 

 completely hydrolyse than the animal has not yet been definitely 

 determined, but it has been found that a much longer hydrolysis is 

 necessary to completely decompose several of them than has been em- 

 ployed by most of those who have studied the animal proteins. Thus 

 Osborne, Leavenworth and Brautlecht (364) found that distinctly more 

 of the basic amino-acids was obtained after boiling several of the seed 

 proteins with 25 per cent, sulphuric acid for twenty-four hours than 

 after boiling for twelve hours, a time usually considered to be quite 

 sufficient to effect complete decomposition of all proteins. That other 

 combinations hydrolysable with difficulty may occur is shown by the pre- 

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