1905] CALDWELL—ACTION OF BROMELIN 417 
Autodigestion occurs most rapidly in alkaline solutions equaling 
m/16~m/32 KOH or NaO, less rapidly in m/10-m/24 HCl, H,SO,, 
or HNO,. Action was inhibited by greater concentrations and 
occurred more slowly in weaker ones. It occurs with poisons in 
strengths very much greater than those inhibiting the action of purer 
. preparations upon egg-albumen, as shown by the following table: 
AUTODIGESTION IN m/24 HC] AT 40° C. 
DILUTION OF MOLECULAR SOLUTION 
SALT a a i ee oe oe 
Inhibited Allowed 
CNB ISOg es aeeoe oe 72 120 
NH,NO, Fi AiNe coemenrer sss sehen fe 2 48 4 64 
EOIN Os Vac Saat also dies 128 256 
rot 0) Fea irae fo eee ae 100 I 
CUS Oped ces eoprenomcns 6,000 8,650 
UNE OD ieee one teld tee lene 16,000 22,750 
FEU) DR APURRRY Oa teas 10,000 16,000 
EIN dlp ecsin oh reiterate fo) fete) 
CON Oa airs ctreneccntte 12 68 
lyr Corey areiy eee aes ahs 1,600 2,400 
INAS CE oars sa Sard siael Ses 150 
In an alkaline medium (m/32 NaOH), inhibiting and allowing 
strengths were uniformly about one-third greater with the few salts 
tested. 
The table just given also represents pretty closely the conditions 
for the digestion of egg-albumen by such impure preparations, in 
so far as this was studied. For example, digestion would just occur 
in m/14000 ZnSO, m/7200 CuSO,, or m/1800 Co(NO,),, as deter- 
mined by decrease in the amount of albumen subjected to the test. 
Hence the degree of susceptibility to poisons is determined largely 
by the purity of the preparation employed, apparently because the 
enzyme is shielded by the associated proteid from the action of 
poisons. The results obtained with preparations of varying purity 
are parallel, 7. e¢., the toxic strengths of different metals bear approxi- 
mately the same relation to each other irrespective of the preparation 
used, 
SUMMARY. 
1. Impure preparations of bromelin are strongly autodigestive 
in acid or alkaline media, such digestion beginning when the breaking 
up of proteid impurities has been completed and proceeding to total 
destruction of the enzyme. 
