i54 
Vines . — The Proteases of Plants (//). 
The autolysis-results bring out once more the specific differences in 
activity between the three samples of papain. The most striking trypto- 
phane-reaction was given by Finkler’s papain, on account, probably, of its 
containing the largest amount of readily proteolysable proteid. With 
respect to the reaction of the liquid, Christy’s and Merck’s samples gave 
better results in acid than in alkaline liquids, whilst Finkler’s was more 
active in alkaline than in acid. As to the antiseptics employed, Christy’s 
papain was active in the presence of HCN, but its action was almost 
entirely inhibited by both toluol and NaF : Finkler’s and Merck’s showed 
about the same activity with all three antiseptics, Finkler’s being especially 
active in the presence of toluol (alkaline). It must be remembered that 
the Merck solution gave a tryptophane-reaction to begin with. 
With the object of obtaining further information as to the relative 
peptolytic activity of the three samples under various experimental con- 
ditions, an experiment was prepared in which such a quantity of readily 
peptolysable proteid was added — in the shape of Witte-peptone — as to 
render negligible, on the whole, whatever amount of proteid may have been 
originally present in the papain. 
I desired, further, that*the experiment should be such as to permit 
of sbme comparison between the fibrin-digesting and the peptolysing 
activity of the papain in each case. In previous observations ( 3 ) I had 
found that these two processes do not necessarily run parallel, and that the 
one may take place without the other. I therefore now added fibrin, as 
well as Witte-peptone, to the bottles in the following experiments. 
Fibrin-digestion and Peptolysis . 
The general method adopted was to extract 8 grms. of papain for 2-3 hours 
with 400 c.c. distilled water, and filter. To the filtered liquid 6 grms. of Witte-peptone 
were added, causing a considerable precipitate in every case. To 120 c.c. of this 
liquid toluol was added to 1 % : to 120 c.c., HCN to 0-2 % ; and to 120 c.c., NaF to 1 %. 
40 c.c. of each of these liquids were put into each of three bottles, to which were 
added respectively either citric acid to 0-5 %, or Na 2 CO s to 0-5 %, or nothing: in the 
last case the reaction was neutral or slightly acid. Finally 0*3 grm. fibrin was added 
to each bottle. The effect of digestion on the fibrin, and the tryptophane-reactions 
were : — 
A. Christy’s Papain. 
Acid. 
Alkaline. 
Natural. 
Toluol 
24 
hours fibrin 
unaltered 
gone 
unaltered 
33 
„ tryptophane 
distinct 
distinct 
faint 
35 
48 
„ fibrin 
not gone 
gone 
gone 
>3 
33 
„ tryptophane 
distinct 
marked 
faint 
