X, A, 1 



Pratt: Papain 



19 



PAPAIN DIGESTION IN ACID SOLUTION 



The following experiments were made to determine the effect 

 of hydrochloric acid on the digestion of milk protein. The 

 digestions were carried out in the usual manner for thirty min- 

 utes at 40°. The results are shown in Table XVI. 



Table XVI. — Papain digestion of milk protein in acid solution. 



No. of 

 flask. 



Milk. 



Water. 



Papain 

 solution. 



Papain. 



Hydro- 

 chloric 

 acid 

 solution. 



Hydro- 

 chloric 

 acid. 



Protein 

 undi- 

 gested. 



Protein 



di- 

 gested. 



Protein 



di- 

 gested. 



Parts of 

 protein 

 digested 

 by 1 part 

 papain. 





ee. 



ce. 



cc. 



mg. 



ec. 



Per cent. 



mg. 



mg. 



Per cent. 





1 



26 



15 



10 



50 







0.00 



651 



505 



43.7 



10.1 



2 



25 



14 



10 



50 



1 



0.02 



671 



485 



42.0 



9.7 



3 



25 



13 



10 



50 



2 



0.04 



670 



486 



42.0 



9.7 



4 



25 



12 



10 



50 



3 



0.06 



719 



437 



37.8 



8.7 



6 



25 



11 



10 



50 



4 



0.08 



750 



406 



35.1 



8.1 



6 



25 



TO 



10 



60 



5 



0.10 



838 



318 



27.6 



6.4 



7 



25 



9 



10 



50 



6 



0.12 



946 



210 



18.2 



4.2 



8 



25 



8 



10 



50 



7 



0.14 



982 



174 



15.1 



S.6 



9 



25 



7 



10 



50 



8 



0.16 



998 



158 



13.7 



3.2 



10 



25 



6 



10 



50 



9 



0.18 



1,000 



156 



13.6 



3.1 



11 



25 



5 



10 



60 



10 



0.20 



1,003 



163 



13.2 



3.1 



Protein in blank = 1,156 milligrams. 



Table XVII. — Papain digestion of milk protein in acid solution. 



No. of 

 flask. 



Milk. 



Water. 



Papain 

 solution. 



Papain. 



Hydro- 

 chloric 



acid 

 solution. 



Hydro- 

 chloric 

 acid. 



Protein 

 undi- 

 gested. 



Protein 



di- 

 gested. 



Protein 



di- 

 gested. 



Parts of 

 protein 

 digested 

 by 1 part| 

 papain. 





ec. 



ce. 



cc. 



mg. 



ec. 



Per cent. 



tng. 



m,g. 



Per cent. 





1 



2S 



20 



5 



25 







0.00 



951 



250 



20.8 



10.0 



2 



25 



19 



5 



25 



1 



0.02 



951 



250 



20.8 



10.0 



3 



25 



18 



5 



25 



2 



0.04 



974 



227 



18.9 



9.1 



4 



25 



17 



6 



25 



8 



0.06 



989 



212 



17.7 



8.6 



6 



25 



16 



5 



25 



4 



0.08 



1.004 



197 



16.4 



7.9 



6 



25 



15 



5 



25 



5 



0.10 



1,060 



141 



11.8 



6.6 



7 



25 



14 



5 



25 



6 



0.12 



1,110 



91 



7.6 



8.6 



8 



25 



13 



5 



25 



7 



0.14 



1,115 



86 



7.2 



3.4 



9 



25 



12 



5 



25 



8 



0.16 



1,123 



78 



6.5 



3.1 



10 



25 



11 



5 



25 



9 



0.18 



1,136 



65 



5.4 



2.6 



11 



25 



10 



5 



25 



10 



0.20 



1,138 



63 



5.3 



2.5 



Protein in blank = 1,201 milligrams. 



The results of this experiment are plotted as curve 1 in 

 fig. 3. This curve shows that amounts of hydrochloric acid up 

 to 0.06 per cent have only a slight retarding action on the diges- 

 tion of milk protein. Increasing amounts from 0.06 to 0.13 

 per cent acid very greatly reduce the activity of the enzjrme, 



