188 The Philippine Journal of Science 1922 
The curves in fig. 2 are the results from further attempts to 
dialyze papain solution: Curve 6, at a temperature of 16° to 
19° C. for four hours; curve 7, at about freezing for sixteen 
hours; and curve 8, at a like temperature for twenty-four hours. 
Even for so short a time as four hours a great decrease in activ- 
ity takes place at 16° to 19° C. Dialysis at temperatures near 
freezing was not successful, since decomposition of the enzyme 
took place, as is indicated by curve 5, fig. 1. 
All the curves in fig. 3 are the results of using 10 cubic 
centimeters of 0.5 per cent papain solution with 25 cubic centi- 
meters of 10 per cent solutions of skimmed-milk powder with 
varying quantities of salts or acids (see Table 1). The total 
volume of the mixture was equal to 50 cubic centimeters. 
In as much as the literature relative to the influence of acids 
and bases on the digestive activity of papain is contradictory, 
it was thought to be worth while to investigate their influence 
and that of several salts. 
The results of the latter investigation are set forth in fig. 3 
and in Table 1. 
TABLE 1.—Influence of various compounds upon the activity of papain. 
| Casein 
C - — Co: f sal d ame 
urve 0: t neentration o: tor acid at at poin 
No. Salt or acid solution. | or acid point of maximum effect. of max- 
solution. mum ef- 
fect. 
Fer eent.| Per cent. Effect. Per cent. 
6 | NaCl... 0 { 0.90 Activates Sara Shed Perea ae 22 
SC.00 +: Initia ica. ce cbc e 9 
Ta. Nas ee ps hae Paps Inhibits at once _____-._---- 26 
8 NSH OOS ccc issse dows ke ts Pp pieiece tian, Fae! Pit ea sete ge Big ua 8.5 
Ds Baik a ctw bbeaeencen. EEN Oe SS as! en Yo § oe eg teaa Sa Se ARTA 29 
0.82 | Activates slightly_-.----..- 41 
10 
— { 20.80 | Inhibits slightly_.....------ 38 
1h? PBOt 2 eee 2 0.82 | Slightly inhibits at once_--- 380 
12 Rs ee 4 Oe Tt A Cty attest neces 45 
18 | Na citrate 6 OO 1. fC eens: Gee in) eavage 52 
14 | CHsCOOH -2o2 a es 2.5 20.50 | Inhibits at once -.-_.---.--- 6 
15 | CHsCHOH COOH --....._.._. 5 21,00 |___-- Pepi arsine Bee ROM esits Wee 18 
8 Maximum concentration used. 
> CaCl, substituted for CuSO, in the precipitation of the milk protein. 
CONCLUSION 
Autolysis of papain takes place at temperatures as low as 
0° C. when the enzyme is put in water solution with toluene 
as an antiseptic. Air-dried samples in sealed glass containers 
