330 IMMUNO-CATALYSIS 



was treated at 95°C., or when Tyrode solution containing 0.025 N 

 NaCN was used as the perfused fluid. A temperature of 95 °C. or 

 NaCN were found to inhibit the enzymes which inactivated the 

 adenyl compounds. While the perfusates from normal tissues were 

 found not to contain either adenyl compounds or the inactivating 

 enzymes, the perfusate of the organs of rabbit and cat treated with 

 cobra venom were found to contain free adenyl compounds and the 

 enzyme inactivating it. 



b. Antibody Against Nucleic Acid-Hydrolyzing Enzymes of 

 Snake Venom. Delezenne and Morel (1919) reported that snake 

 venoms hydrolyzed both yeast and thymus nucleic acids and that the 

 enzymes responsible for this effect were completely neutralized by 

 anti-venom serum. 



A carefully neutralized saline solution of yeast nucleic acid was 

 treated with 0.1 per cent saline solution of snake venom and incubated 

 at 50°C. In the presence of cobra venom, for example, nucleic acid 

 lost its precipitability with hydrochloric acid. Thymus nucleic acid, 

 which is very gelatinizable and solidifies in the cold, lost this property 

 following the action of snake venom. They found that the time re- 

 quired for the unhydrolyzed thymus nucleic acid to gelatinize in the 

 cold was proportional to the amount of the venom added. After a few 

 hours incubation with the venom, thymus nucleic acid lost this prop- 

 erty completely, and it did not assume viscous consistency even at ice- 

 water temperature. 



On the other hand, reaction mixtures neutral to phenolphthalein 

 became markedly acid to litmus as the result of the formation of phos- 

 phoric acid and sodium acid phosphate. The development of acidity, 

 followed by titration with alkali, was found to progress with the 

 enzyme hydrolysis. The titration curve was typical of an enzyme re- 

 action. The enzyme activity of the venom was completely inhibited 

 in the presence of an optimal amount of antivenom specific serum. 



They observed that the venom of colubrides, which possesses most 

 marked general toxicity, was also the one which most readily hydro- 

 lyzed nucleic acid. In contrast, the venom of viperides, which was 

 stated to be much less active, was found also not to exercise hydrolytic 

 activity on nucleic acid under the experimental conditions employed. 



c. Inhibition of Ribonuclease by Homologous Anti-Serum. 

 Kunitz (1940) isolated a crystalline protein from beef pancreas capable 



