THE DIGESTIVE PROPERTIES OF PHILIPPINE PAPAIN? 
By HArvey C. BRILL and Rogert E. BROWN 
THREE TEXT FIGURES 
Many methods have been proposed and their efficiency tested 
for measuring the proteolytic properties of papain and of other 
proteolytic enzymes. Some of these methods will be found in 
the references cited.” 
D. S. Pratt > made use of a 40 per cent solution of sweetened, 
condensed, skimmed milk as his substrate and a 0.5 per cent 
water solution of papain as his enzyme solution. In his experi- 
ments these solutions were mixed and at the end of the digestion 
time the undigested casein was precipitated by the addition of 
0.5 cubic centimeter of copper sulphate solution (60 grams per 
liter) followed by 0.5 cubic centimeter of glacial acetic acid ac- 
companied by vigorous stirring during the precipitation. The 
precipitated casein was broken up, washed several times on 
the filter, dried in the oven, and weighed. By making use of 
a blank the percentage of casein digested was calculated. This 
method was thoroughly tried out, and reliable results were ob- 
tained in his investigation. Because of its simplicity and *reli- 
ability we have adopted the same method in our work. 
EXPERIMENTAL 
Several samples of papain which had been used by Pratt in 
his work in 1914 were examined by us (seven years later) for 
proteolytic activity, and found to have lost all such activity. 
These samples represented papain that was extremely active 
* Contribution from the chemical laboratory of Miami University, Oxford, 
io. 
*Delauny and Bailly, Bull. Sci. Pharm. 20 (1913) 241; Van Dam, W., 
Z. physiol Chem. 79 (1918) 247; Mendel, L. B., and Blood, A. F., Journ. 
Biol. Chem. 8 (1910) 177; Long, J. H., and Barton, A. W., Journ. Am. 
Chem. Soc. 36 (1914) 2151; Sherman, H. C., and Neun, D. E., ibid. 38 
(1916) 2199; Falk, Chemistry of Enzymes, Chem. Cat. Co. (1921); ete. 
*Philip. Journ. Sci. § A 10 (1915) 1. 
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