214 IMMUNO-CATALYSIS 



1. Antibody Against Emulsin 



In 1893 Hildebrandt reported that the injection of emulsin prepared 

 from almonds into rabbits caused loss of weight and finally death. 

 Injecting 0.3 to 0.9 g. of emulsin rectally into rabbits daily, and increas- 

 ing the amount of emulsin to 1 g. during the second week the animal 

 did not lose weight and no other pathological symptoms were observed. 

 Injecting 1 g. of emulsin rectally in one dose caused, however, the 

 death of control rabbits within 24 to 48 hours. On the basis of these 

 results, he believed the animal which received emulsin in small doses 

 during one week had developed local immunity. In subsequent experi- 

 ments he resorted to the immunization of rabbits by subcutaneous 

 injections. He first injected an initial dose of 0.01 g. of emulsin and 

 increased the dose gradually to 1 g. (dissolved in 20 ml. of 0.6 per cent 

 sodium chloride solution). No injury was suffered by the rabbit. In 

 contrast, the control rabbits succumbed within one week after receiv- 

 ing 0.1 g. and two days after receiving 0.5 g. of emulsin. 



The action of emulsin on amygdalin produces hydrocyanic acid. 

 The formation of this poison in vivo by injecting the enzyme and the 

 substrate into a rabbit was proven by the instantaneous death of the 

 animal with the symptomatology of cyanide poisoning. 



H 



/ 



CeHs— C +2H20-fEmulsin->C6H6CHO-f2C6Hi206-|-HCN 



\ 



O- Ci2H2lOio 



Amygdalin 



The simultaneous intravenous injection of 0.03 g. of emulsin and 

 0.5 g. of amygdalin into a normal rabbit caused the death of the animal 

 within less than one minute from cyanide poisoning. In contrast in 

 a rabbit immunized against emulsin and treated as above, the cyanide 

 poisoning did not appear until after a period of six to seven minutes 

 had elapsed. Hildebrandt expressed his observations as follows: "Diese 

 Thatsache spricht zweifellos dafiir, dass es sich bei der Emulsin festig- 

 keit nicht bios um eine Immunitat der Zellen des Organismus gegen 

 die Giftwirkung des Fermentes handelt, sondern dass eine Art Gegen- 



