24 



The Philippine Journal of Science 



1!)1S 



Portions were removed and tested with bromine water for 

 tryptophane. Nos. 1 and 3 gave no color, while No. 2 gave a 

 pronounced purple after twenty-four hours' incubation. These 

 results are in accord with the data given by Mendel and Blood.' 

 working with commercial material. 



DIGESTION AT VARIOUS TE.MPERATURES 



Digestions of milk protein were carried out in the usual manner 

 at temperatures ranging from 0' to 70 to determine the activity 

 of papain under these conditions. The papain used in these de- 

 terminations was prepared by the alcohol precipitation method, 

 and was very active. All digestions were for thirty-minute 

 periods. That at 0° was carried out with all fla.sks surrounded 

 by finely cracked ice, contained in a well-insulated thermostat. 

 The temperature was not allowed to rise until after the final 

 precipitation with copper sulphate and acetic acid. The analysis 

 is shown in Table XX. 



Table XX. — Papain digestion of inillc protein at 0'. 



No. of 

 flask. 



Milk. 



Water. 



Papain 

 solution. 



Papain. 



m 



Protein 

 digetited. 



Protein 

 digested. 



Parts of 

 protein 

 digested 

 by 1 part 

 papain. 





ee. 



ee. 



ee. 



mg. 



mo. 



mo. 



fereant. 





1 



25 



23 



2 



10 



1,102 



38 



8.8 



3.8 



2 



25 



21 



4 



20 



1.048 



92 



8.1 



4.6 



3 



25 



19 



6 



30 



993 



147 



12.9 



4.9 



4 



26 



17 



8 



40 



987 



153 



13.4 



3.8 



6 



26 



16 



10 



SO 



922 



218 



19.1 



4.4 



6 



26 



13 



12 



60 



861 



279 



24.4 



4.7 



7 



26 



11 



14 



70 



827 



313 



27.4 



4.8 



8 



25 



9 



16 



80 



817 



328 



28.4 



4.0 



9 



26 



7 



18 



90 



789 



351 



30.8 



3.9 



10 



26 



5 



20 



100 



756 



384 



33.7 



3.4 



Protein in blank = 1,140 milligmuns. 



Papain shows a remarkable activity at low temperatures, as 

 may be seen from the curve in fig. 4 plotted from the above 

 analysis. 



The results of a series of digestions run at 10° are shown in 

 Table XXI. 



' Loc. cit. 



