68 
The  Function  of  Enzymes. 
\  Am.  Jour.  Pharm. 
(   February,  i915. 
solutions  a  small  amount  of  maltose  (or  isomaltose,  a  similar  sugar) 
will  be  formed,  the  reaction  proceeding  until  a  certain  equilibrium 
is  established.  This  has  not  been  demonstrated  for  all  enzymes,  and 
some  eminent  authorities  divide  enzymes  into  two  classes,  only  one 
of  which  is  catalytic  and  capable  of  synthesizing  as  well  as  splitting 
substances,  while  in  the  other  no  trace  of  synthesis  has  been  observed. 
On  the  subject  of  the  origin  of  enzymes  and  the  causes  stimulat- 
ing their  activity  many  interesting  observations  have  been  made. 
Some  enzymes  are  produced  by  cells  in  such  form  as  to  require  no 
further  aid  to  render  them  active.  Others  require  the  presence  of 
a  specific  substance  known  as  an  activator.  The  pepsin  of  the 
stomach  is  produced  by  the  cells  of  the  gastric  glands  as  a  zymogen 
called  pepsinogen,  which,  under  the  influence  of  the  hydrochloric 
acid  produced  at  the  time  the  stomach  is  functioning,  becomes  changed 
to  pepsin.  We  do  not  know  how  the  enzyme  and  the  acid  are  asso- 
ciated, but  we  know  that  the  latter  is  necessary  for  the  production  of 
pepsin  and  also  for  its  action.  Bayliss  has  described  another  instance 
in  which  the  activator  itself,  enterokinase,  acts  as  an  enzyme  upon  the 
zymogen,  trypsinogen,  thus  producing  trysin,  but  without  entering 
into  the  actual  formation  of  the  finished  enzyme — trypsin.  If  this 
view  is  correct,  we  have,  in  effect,  one  enzyme  bringing  a  second  into 
existence.  In  other  instances,  activation  is  effected  by  metals,  as  in 
the  laccase,  the  oxidizing  enzyme  of  the  lac  tree  of  Asia,  which  re- 
quires manganese ;  or  by  salts,  such  as  phosphates,  as  in  certain  al- 
coholic fermentations. 
In  spite  of  the  apparent  lack  of  exact  knowledge  of  the  composi- 
tion of  enzymes  and  of  all  their  activities,  we  find  in  this  group  of 
substances  agents  which  are  of  direct  and  certain  application  to 
industrial  processes.  Bread-making,  brewing,  cheese-making,  certain 
phases  of  tanning,  as  well  as  the  preparation  of  lacquers  and  castor 
oil,  are  a  few  of  these  applications. 
Here  is  a  field  of  great  promise  and  infinite  interest,  sure  to 
yield  results  if  investigated  patiently  and  consistently  by  the  scientist 
who  combines  a  deep  knowledge  of  organic  chemistry  with  an  in- 
timate acquaintance  with  cell  behavior  and  activity,  and  this  field 
of  bio-chemistry  is  sure  to  find  greater  favor  in  the  immediate 
future. 
