X, A, 1 



Pratt: Papain 



17 



pain. All of the flasks contained the same amounts of milk, 

 water, and enzyme solution, but were maintained at 40° for vary- 

 ing lengths of time before precipitation. The results of this 

 series are shown in Table XV. The papain used was sample 

 6 from Ceylon. 



Table XV. — Rate of digestion of milk protein. 



No. of 

 flask. 



Time of 

 digestion. 



Protein 

 undi- 

 gested. 



Protein 

 digested. 



Protein 

 digested. 



Parts of 

 protein 

 digested 

 by 1 part 

 papain. 





Mins. 



mg. 



mg. 



Per cent. 





1 



10 



862 



281 



24.7 



11.2 



2 



20 



816 



327 



28.6 



13.1 



3 



30 



783 



360 



31.5 



14.4 



4 



40 



760 



383 



33.5 



15.3 



5 



50 



741 



402 



35.1 



16.0 



6 



60 



714 



429 



37.5 



17.0 



7 



70 



703 



440 



38.4 



17.6 



8 



80 



702 



441 



38.5 



17.6 



9 



90 



708 



435 



38.1 



17.4 



10 



100 



664 



479 



41.8 



19.1 



11 



110 



685 



458 



40.1 



18.0 



12 



120 



675 



468 



40.9 



18.7 



13 



130 



681 



462 



40.3 



18.5 



14 



140 



668 



475 



41.6 



19.0 



15 



150 



658 



485 



42.4 



19.4 



Protein in blank = 1,143 milligrams. 



Each flask contained 25 cubic centimeters of milk, 20 cubic centimeters of water, and 5 

 cubic centimeters of enzyme solution equivalent to 25 milligrams of papain. 



These results are plotted in fig. 2. An inspection of this curve 

 shows that digestion proceeded rapidly during the first ten min- 

 utes and practically reached its maximum within an hour. The 

 nature of the protein and conditions of solution, concentration, 

 etc. would affect the equilibrium to a greater or less extent, so 

 that this period of digestion must not be taken as applying to 

 some other substrate, such as beef. 



DIGESTION UNDER VARIOUS CONDITIONS 



The literature of papain contains many conflicting statements 

 regarding the conditions suitable for digestion. Some authors 

 claim that the enzyme acts in neutral, alkaline, or acid solu- 

 tion; others, that one or the other is best suited for proteolytic 

 activity. The question is important in its bearing upon the use of 

 papain as a medicinal agent and interesting in comparing papain 

 with other enzymes, such as pepsin and trypsin. 



131717 2 



