PROTEOLYTIC ENZYMES 95 



The amount and kind of each of the decomposition 

 products produced by these proteolytic enzymes are 

 dependent upon the nature of the protein attacked and 

 on the temperature, acidity, or alkalinity, and other factors 

 of the reaction. 



From the peptic digestion of casein a proteose (caseose) 

 is obtained which contains all the phosphorus of the 

 casein, later peptones arise, as well as paranuclein and 

 paranucleic acids. 



With trypsin it is broken down more rapidly into 

 caseose, caseone (an antipeptone residue), tyrosine, and 

 some other simple products. 



Gelatine is converted into primary and secondary 

 gelatoses, gelatine peptones, and, according to Nencki, 

 a certain amount of leucine, glycocoll, and ammonia. 



Ex. 54. Take three large test-tubes and label them A, B, C 

 respectively. 



Half-fill each with a i per cent, solution of sodium carbonate 

 and add five or six drops of Benger's Liquor pancreaticus, which 

 contains trypsin. 



Boil A, and then cool it. 



Add a drop or two of hydrochloric acid to B, so as to make 

 it acid instead of alkaline. 



Leave C alone. 



Then add to each a piece of fibrin which has been washed and 

 soaked for half an hour in i per cent, sodium carbonate solution. 



Place the tubes in a water bath at 40 C. for half an hour. 



Examine them at intervals and note that in A no change is 

 observable, the ferment having been destroyed by boiling. 



In B digestion does not occur, the solution being acid. 



In C the fibrin is eaten away and dissolved without swelling 

 up, as in pepsin digestion. 



(a) Filter the liquid in C and test a small portion for alkali- 



