186 IMMUNO-CATALYSIS 



that enzymes adsorb on charcoal, alumina, Fuller's earth, etc. in a 

 manner similar to the adsorption of toxins on these adsorbents. 

 However, one very seldom carries out immune reactions in the pres- 

 ence of such adsorbents; secondly, it does not necessarily lead to the 

 inactivation of the enzymes or toxins. The decrease of the activity or 

 absence of inactivation in the adsorbed state depends on what particu- 

 lar groups of the enzymes or toxins have been blocked by the adsorption 

 process. 



Griffin and Nelson (1916) found that invertase adsorbed on alumi- 

 num hydroxide or on small amounts of charcoal is just as active enzy- 

 matically as the solution of free enzyme. The presence of egg-albumin 

 in invertase solution likewise does not affect the enzyme activity. 

 Michaelis (1921) reported that invertase adsorbed on Fuller's earth or 

 iron oxide, likewise, is just as active as the free enzyme. Fructose, 

 mannose, lactose, a- and )8-methylglucoside fail to elute the enzyme 

 from the adsorbent. Sucrose and raffinose which are hydrolyzed, and 

 maltose which is not hydrolyzable by invertase, slowly promote the 

 elution of the enzyme. These facts show that the elution effects of the 

 former two substances are not related to their being substrates for the 

 enzyme. On the other hand, those substances, glucose, fructose, man- 

 nose, a-methylglucoside, which show a great affinity for and thereby 

 inhibit invertase activity, fail to effect the elution of the enzyme. 



According to Kleczowski (1944) invertase adsorbed on charcoal 

 can be set free by casein, and it can be extracted by tobacco mosaic 

 virus, but not by sucrose. 



Oparin and Kurssanow (1929) precipitated invertase by tannic acid; 

 in this state invertase was inactive. It is interesting to note that by 

 shaking the tannic acid precipitate of the invertase preparation with 

 egg albumin or peptone they stated they had formed egg albumin- 

 tannate, or peptone-tannate precipitates, setting free the invertase in 

 an active form. Evidently egg-albumin-tannate, or peptone-tannate 

 precipitates are incapable of adsorbing the liberated invertase. 



Freund (1931) reported that tannin detoxifies diphtheria and tetanus 

 toxins in solution or adsorbed on collodion particles. This effect oper- 

 ates in vitro as well as in vivo. Tannin combining with the toxins 

 produces a precipitate. The degree of detoxification runs parallel with 

 the amount of precipitate formed. However, this effect is reversible 

 at pH 8, or in high dilutions, and the toxin is recovered in an intact 



