388 IMMUNO-CATALYSIS 



of antiserum was found to correspond to a half maximal inhibition of 

 the enzyme and presumably half combined with antibody. 



On the basis of the above results it is clear that a combination be- 

 tween the enzyme and its specific antibody prevents a contact, or com- 

 bination between the enzyme protein and its coenzyme group. On 

 the other hand, a combination between the enzyme protein and the 

 coenzyme inhibits from 40 to 50 per cent the combination between 

 the enzyme protein and its specific antibody. These data could be 

 interpreted to indicate that both the antibody and coenzyme DPN 

 exercise combining affinities for the same groupings on the enzyme 

 molecule. The combination between the enzyme and antibody being 

 weakly dissociable would explain the greater degree of inhibition of 

 enzyme activity shown when the reaction between enzyme and anti- 

 body occurs in the absence of coenzyme. Weak dissociability of the 

 enzyme-antibody complex would likewise explain a partial inhibition 

 of enzyme activity by the addition of an excess amount of antiserum to 

 a reaction system which is proceeding at maximum speed. 



5. Reports on the Inhibition of Bacterial Respiration by 

 Specific Immune Serum 



Amako (1930), Braun and Vasarhelyi (1932) studied the de- 

 hydrogenase activities of bacteria using the reduction of methylene blue 

 (Thunberg method) as a measure. They stated that the reduction of 

 methylene blue is appreciably inhibited in the presence of immune 

 serum. Suranyi and Paloczy (1930) measured the respiration of B. 

 fyocyaneus with the Barcroft- Warburg set-up. They stated that in the 

 presence of specific agglutinating serum, the respiration was appreci- 

 ably inhibited. In the presence of immune serum and complement, 

 following an initial increase, the respiration was completely inhibited. 

 Wohlfeil (1933) studied the respiration of the typhoid group of bacilli 

 in the presence of various amounts of agglutinating serum. He stated 

 that the respiration of motile bacilli was inhibited in the presence of 

 agglutinating serum. On the other hand, the respiration of non-motile 

 bacilli was stated to experience an increase in the presence of ag- 

 glutinating serum. 



Study of the Effect of Immune Reactions on the Metaholism of 

 E. Typhosa and Pneumococcus. A study was initiated by Sevag 



