﻿The 
  Biological 
  Significance 
  of 
  Anaphylaxis. 
  143 
  

  

  escape 
  raceniisation 
  are 
  those 
  occupying 
  the 
  terminal 
  positions 
  in 
  the 
  peptide 
  

   chains, 
  out 
  of 
  which 
  the 
  large 
  protein 
  molecule 
  is 
  supposed 
  to 
  be 
  built. 
  

  

  Dudley 
  and 
  Woodman* 
  found 
  that 
  the 
  caseins 
  from 
  sheep's 
  and 
  cow's 
  

   milk, 
  though 
  containing 
  the 
  same 
  amino-acids 
  in 
  the 
  same 
  proportions, 
  

   showed 
  a 
  small 
  but 
  definite 
  difference 
  when 
  examined 
  by 
  this 
  method. 
  The 
  

   amino-acids 
  escaping 
  racemisation 
  were 
  not 
  identical 
  in 
  the 
  two 
  cases. 
  

  

  It 
  seemed 
  of 
  interest 
  to 
  determine 
  directly 
  whether 
  a 
  difference 
  of 
  this 
  kind 
  

   could 
  be 
  related 
  to 
  a 
  difference 
  of 
  behaviour 
  as 
  anaphylactic 
  antigens. 
  Dr. 
  Dakin 
  

   and 
  I 
  decided 
  to 
  make 
  the 
  comparison 
  on 
  the 
  crystallised 
  albumins 
  from 
  

   the 
  eggs 
  of 
  the 
  domestic 
  fowl 
  and 
  the 
  duck. 
  Dr. 
  Dakin 
  prepared 
  the 
  two 
  

   pure 
  proteins 
  and 
  conducted 
  the 
  analysis. 
  The 
  two 
  are 
  indistinguishable 
  by 
  

   any 
  ordinary 
  method. 
  Their 
  physical 
  properties 
  appear 
  to 
  be 
  identical, 
  and 
  

   they 
  contain 
  the 
  same 
  amino-acids 
  in 
  apparently 
  identical 
  proportions. 
  The 
  

   results 
  of 
  the 
  racemisation 
  are 
  shown 
  in 
  Table 
  I. 
  The 
  difference 
  is 
  small 
  

   but 
  quite 
  definite, 
  and 
  might 
  well 
  be 
  supposed 
  to 
  correspond 
  with 
  a 
  far 
  

   greater 
  difference 
  in 
  the 
  structure 
  of 
  the 
  whole 
  molecule. 
  What 
  we 
  have 
  

   here 
  is, 
  as 
  it 
  were, 
  an 
  imperfect 
  glimpse 
  of 
  the 
  edge 
  of 
  the 
  pattern. 
  Figs. 
  11, 
  

   12, 
  and 
  13 
  show 
  their 
  behaviour 
  as 
  anaphylactic 
  antigens, 
  the 
  tracings 
  being 
  

   again 
  records 
  of 
  the 
  contraction 
  of 
  the 
  isolated 
  uterine 
  muscle 
  of 
  specifically 
  

   sensitised 
  guinea-pigs. 
  Fig. 
  11 
  is 
  from 
  a 
  guinea-pig 
  sensitised 
  to 
  hen-albumin. 
  

   Figs. 
  12 
  and 
  13 
  are 
  from 
  two 
  horns 
  of 
  the 
  uterus 
  of 
  a 
  guinea-pig 
  sensitised 
  

   to 
  duck-albumin. 
  

  

  Table 
  I. 
  

  

  Amino-acid. 
  

  

  State 
  of 
  optical 
  activity. 
  

  

  Comments. 
  

  

  " 
  Eaceinised 
  " 
  hen- 
  

   albumin. 
  

  

  " 
  Eacemised 
  " 
  duck- 
  

   albumin. 
  

  

  Proline 
  

  

  Phenylalanine 
  

  

  Aspartic 
  acid 
  ... 
  

   Glutamic 
  acid 
  

  

  Lysine 
  

  

  Not 
  racemised 
  

   Partly 
  racemised 
  

   Mostly 
  racemised 
  

   Mostly 
  racemised 
  

   Completely 
  inactive 
  

   Inactive 
  

   Mostly 
  inactive, 
  some 
  active 
  

   Completely 
  inactive 
  

   Completely 
  inactive 
  

   Active 
  

   Inactive 
  

  

  Not 
  racemised 
  

   Partly 
  racemised 
  

  

  Mostly 
  active 
  

   Mostly 
  racemised 
  

   Completely 
  inactive 
  

  

  Inactive 
  

   Completely 
  inactive 
  

   Completely 
  inactive 
  

   Mostly 
  active 
  

   Active 
  

   Inactive 
  

  

  No 
  difference. 
  

  

  No 
  difference. 
  

   A 
  definite 
  difference. 
  

  

  No 
  difference. 
  

  

  No 
  difference. 
  

  

  No 
  difference. 
  

   Definite 
  difference. 
  

  

  No 
  difference. 
  

   Definite 
  difference. 
  

  

  No 
  difference. 
  

  

  No 
  difference. 
  

  

  It 
  must 
  not 
  be 
  assumed 
  that 
  all 
  antigenic 
  difference 
  necessarily 
  depends 
  on 
  

   this 
  kind 
  of 
  structural 
  difference. 
  There 
  is 
  evidence, 
  for 
  example, 
  in 
  favour 
  

   of 
  the 
  view 
  that 
  the 
  euglobulin 
  and 
  pseudo-globulin 
  of 
  a 
  serum 
  represent 
  

   * 
  'Biochem. 
  Journ.,' 
  vol. 
  9, 
  p. 
  97 
  (1915). 
  

  

  M 
  2 
  

  

  