384 



IMMUNO-CATALYSIS 



The results presented here show that rabbit immune serum prepared 

 against partially purified yeast hexokinase completely inhibits its 

 activity. 



The high specificity of this reaction is indicated by the fact that: (a) 

 a rabbit immune serum prepared against the same enzyme preparation 

 suspended in Falba-mineral oil, even though it produced an immune 

 serum with higher precipitating and complement-fixing titer, was 

 incapable of exercising an inhibitory effect on the hexokinase activity; 

 (b) a rabbit immune serum prepared against streptococcal hyaluronid- 

 ase likewise failed to inhibit hexokinase activity; and (c) an aqueous 

 extract of rat brain (8 ml. of chilled distilled water per rat brain) as 



400 — 



300 — 



ZOO 



8^ 



^ 



100— 



Minutes 



Fig. 2. Inhibitory eflFect on yeast hexokinase by homologous rabbit antiserum 

 added after the reaction had proceeded for 20 minutes. 



