X, A, 1 



Pratt: Papain 



and the papers are dried to constant weight at 100°. No cor- 

 rection for the amount of papain used is necessary, as it is not 

 precipitated by copper sulphate and acetic acid. 



The weight of protein digested by the various amounts of 

 papain may be calculated from the blank in which no enzyme was 

 used. The entire determination with the exception of drying 

 may be made in from three to four hours, and duplicate analyses 

 agree within about 2 per cent. The curves obtained in this 

 manner show at a glance the relative proteolytic power possessed 

 by samples of papain, as well as the rate at which digestion has 

 proceeded with increasing amounts of enzyme. No antiseptic 

 is necessary with such short periods of incubation. 



Analyses were carried out in this manner with commercial 

 samples of papain from various sources. A great divergence 

 in activity waS encountered, ranging from gum possessing prac- 

 tically no proteolytic power to highly active material. The 

 curves obtained from these data are plotted in fig. 1. 



ANALYSES OF PAPAIN 



No. 1. Papain from local drug store. — This sample was of un- 

 known origin, and had been obtained from Germany several years 

 previously. It was light colored, and possessed an odor resem- 

 bling pepsin. A small portion boiled with water gave a positive 

 test for starch with iodine solution. The analysis is shown in 

 Table II. 



Table II. — Analysis of papain, sample 1. 



No. of 

 flask. 



Milk. 



Water. 



Papain 

 solution. 



Papain. 



Protein 

 undi- 

 gested. 



Protein 



digested. 



Protein 

 digested. 



Parts of 

 protein 

 digested 

 by 1 part 

 papain. 





ce. 



cc. 



cc. 



nig. 



mg. 



ma. 



Per cent. 





1 



25 



23 



2 



10 



1.160 







0.0 





2 



25 



21 



4 



20 



1,163 







0.0 





3 



25 



19 



6 



30 



1,159 







0.0 





4 



25 



17 



8 



40 



1.151 



4 



0.3 



0.1 



5 



25 



15 



10 



50 



1,149 



6 



0.5 



0.1 



6 



25 



13 



12 



60 



1,132 



22 



1.9 



0.3 



7 



25 



11 



14 



70 



1,116 



39 



3.4 



0.5 



8 



25 



9 



16 



80 



1,107 



48 



4.2 



O.B 



9 



25 



7 



18 



90 



1,098 



57 



5.0 



0.6 



10 



25 



5 



20 



100 



1,092 



63 



6.0 



0.6 



Protein In blank = 1,155 milligrams. 



Acidity of papain solution as HCl =0.005 per cent. 



The sample was practically inert, although it retailed at 1 peso (50 cents) per 20 grams. 



