1 76 
Note  on  Trypsin. 
(Am.  Jour.  Pharm. 
<-      March,  1919. 
doubtful  whether  the  precipitate  was  a  compound  of  trypsin  and 
safranine. 
The  method  of  purification  of  the  enzyme  which  I  adopted  is  a 
very  simple  one,  and  so  far  as  I  know  has  not  been  previously  de- 
scribed; it  depends  on  the  fact  that  cellulose  absorbs  the  impure 
compound  of  proteins  and  enzymes,  and  that  after  drying,  the  col- 
loidal protein  portion  adheres  firmly  to  the  paper,  whereas  the  en- 
zyme is  very  easily  soluble.    The  method  is  as  follows : 
Ordinal  circles  of  Swedish  filter  paper  (J.  H.  Munktell)  12^ 
cm.  diam.,  area  122  sq.  cm.,  ash  0.00095  Gm.,  averaging  in  weight 
0.87  Gm.  air-dry,  were  soaked  in  the  impure  enzyme  solution,  and 
dried  quickly  in  a  current  of  hot  air.  The  average  increase  in  weight 
was  0.054  Gm.,  i.  e.,  they  contain  about  6.0  per  cent,  of  added  matter, 
or  0.41  mgrm.  per  sq.  cm.  When  such  paper  is  placed  in  water,  the 
enzyme  dissolves  quickly  to  a  perfectly  clear  solution  in  a  few 
minutes,  but  the  colloidal  matter  with  which  it  is  associated  adheres 
firmly  to  the  paper;  the  solution  is  filtered  after  15-20  minutes,  by 
which  time  the  whole  of  the  enzyme  matter  is  dissolved.  If  left 
for  a  longer  time,  proteins  begin  to  dissolve,  and  the  enzyme  strength 
decreases. 
When  a  solution  of  safranine  is  added  to  the  enzyme  solution 
prepared  in  this  way,  no  precipitate  is  produced,  and  the  solution 
passing  through  the  filter  is  as  active  as  the  original  solution,  due 
account  being  taken  of  the  dilution.  The  following  experimental 
results  were  obtained:  1.8366  Gm.  of  the  paper  impregnated  with 
enzymes  was  stirred  in  183  Cc.  of  distilled  water  for  15  minutes, 
and  then  filtered;  0.6  Cc.  of  the  filtrate  was  found  to  liquefy  the 
standard  gelatin  tube  under  the  same  conditions  as  in  the  test 
previously  described8  corresponding  to  6  mgrms.  of  the  paper.  The 
6  mgrms.  of  paper  contained  0.34  mgrm.  of  original  extract. 
A  test  of  the  original  extract  showed  0.35  mgrm.  of  matter 
capable  of  liquefying  the  gelatin,  but  the  soluble  matter  is  the  6 
mgrms.  of  paper  was  found  by  evaporation  of  the  filtrates  to  be 
0.23  mgrm.,  so  that  the  enzyme  has  been  purified  to  this  extent; 
*•  e->  35  Per  cent-  of  non-enzyme  matter  has  been  removed.  For 
comparison  it  may  be  useful  to  give  results  for  Griibler's  pancreatin, 
which  I  have  always  used  as  a  standard  of  comparison :  it  is  labelled 
"Pankreatin  Dr.  G.  Griibler  &  Co.,  Leipzig";  0.1  Gm.  dissolved  in 
about  30  Cc.  of  alkaline  water  digests  8-10  Gms.  of  moist  blood 
8  Journal  of  Society  of  Chemical  Industry,  912,  1105. 
