CHAPTER V. 



THE ACTION OF THE ENZYMES FOUND IN THE HUMAN 

 ALIMENTARY TRACT. 



i. Amylase (ptyalin, amylopsin, diastase) is the term 

 applied to the enzyme found in the salivary and pancreatic 

 .secretions, which has the power of acting upon starch and 

 producing from it maltose and dextrin. The ferment is 

 found in other tissues of the body also, as well as in germinat- 

 ing cereals of all kinds (rice, corn, oats, etc.)- The alimentary 

 secretions of all animals do not contain amylase. The saliva 

 of the dog, for instance, contains no starch-splitting ferment, 

 and the same seems to be true of all carnivora. The amylase 

 of the parotid sterns to be present in the human being im- 

 mediately after birth, but the starch-splitting ferment of the 

 pancreas does not appear until a month or more later. 



We recognize the presence of amylase by its power of acting 

 upon starch and its ready destruction by heat rather than by 

 any analytical means at our disposal. As with practically all 

 enzymes, amylase has not yet been obtained in a pure state. 

 COHNHEIM J has succeeded in obtaining the amylase of the 

 saliva as a gray powder of fairly constant composition by 

 acidifying the collected saliva with phosphoric acid and 

 neutralizing subsequently with dilute calcium hydroxide. 

 The amylase is carried down mechanically with the precipi- 

 tate of calcium phosphate, and after filtering is redissolved by 

 the addition of water. From this aqueous solution the amylase 

 can be reprecipitated by alcohol in order to further purify it. 



1 COHNHEIM: Virchow's Archiv, 1863, XXVIII, p. 241. 



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