Enzymes  and  Their  Importance. 
f  Am.  Jour.  Pharm. 
{  December,  1913. 
able  to  explain  them.  Diastase  was  discovered  in  1814,  and  in  183 1 
the  identity  of  its  action  with  that  of  ptyalin  in  the  saliva  was 
established. 
Over  one  hundred  and  twenty  enzymes  are  at  present  known, 
and  the  action  of  the  majority  of  these  consists  in  splitting  up  or 
transforming,  although  there  is  an  increasing  number  of  observations 
dealing  with  the  synthetic  role  of  enzymes.  It  has  been  possible  to 
build  up  isolactose  from  d-glucose  and  d-lactose,  and  recently  even 
the  glucoside  amygdalin  has  been  built  up  with  the  aid  of  yeast  mal- 
tase.  It  may  be  safely  assumed  that  these  building-up  enzymes  play 
a  great  part  in  the  synthesis  of  plant  substances.  Of  great  interest 
is  the  fact  that  enzymatic  processes  may  be  reversed,  as  was  shown 
in  1898  by  Croft  Hill,  who  proved  that  a  reversible  zymohydrolysis 
was  possible. 
To  understand  the  processes  which  take  place  in  the  living  medici- 
nal plant  and  in  its  transformation  into  a  drug  and  then  in  the  latter 
itself,  it  is  necessary  to  pass  in  review  the  best-known  enzymes.  The 
first  and  largest  group,  and  the  first  to  be  known,  is  that  of  the 
hydrolases  or  hydratases,  among  which  the  carbohydrases  are  dis- 
tinguished by  their  property  of  splitting  up  polysaccharides.  To 
this  group  belong  the  biases  or  disaccharases,  such  as  invertase,  mal- 
tase,  trehalase,  gentiobiase,  and  the  triases  or  trisaccharases,  such  as 
raffinase,  gentianase,  rhamninorhamnase  and  stachyase,  as  well  as 
the  polysaccharases,  such  as  amylase,  which  splits  up  starch  and  is 
also  known  under  the  name  of  diastase,  cellulase  (or  zytase),  inulase, 
seminase,  pectinase,  xylenase,  and  gelase. 
The  glucosidases,  the  enzymes  capable  of  splitting  up  glucosides, 
are  widely  distributed,  and  their  principal  representative  is  emulsin, 
which  splits  up  amygdalin.  A  large  number  of  these  are  named  with 
reference  to  their  respective  glucosides,  and  include,  inter  alia,  popu- 
linase,  phloridzinase,  salicylase,  arbutase,  gaultheriase,  rhamnase, 
myrosinase  (myrosin),  tannase.  Another  class  of  the  hydratases 
are  the  ester-splitting  esterases,  to  which  belong  the  fat-splitting 
lipase,  and  chlorophyllase,  which  is  present  with  chlorophyll. 
A  particularly  important  group  is  that  of  the  proteases  and 
amidases,  which  includes  pepsin  and  trypsin — pepsin  belongs  to  the 
proteases.  Another  group,  the  coagulases,  is  mainly  represented  in 
animal  organisms,  and  to  it  belongs  chymase,  or  rennet,  which  causes 
the  coagulation  of  milk.  Of  considerable  importance  to  us  are  the 
oxydases,  which  possess  the  property  of  causing  oxidation  in  the 
