LEVINE, BIOCHEMICAL STUDIES OF SELENIUM 391 



Effect of Selenium Compounds upon Catalase and Other 



Enzymes 



catalase 



The compounds of selenium employed in enzyme investigations were 

 selenium dioxid (selenious acid), selenic acid, sodium selenite, sodium 

 selenate and potassium selenocyanate. The effect upon catalase was 

 determined as follows : Healthy, normal dogs were bled to death from 

 the femoral aiteTj, using cocaine as a local anesthetic. Weighed 

 amounts of defibrinated blood and tissues were ground with sand and 

 mortar, treated with 40 c. c. distilled water and 10 c. c. chloroform and 

 permitted to extract twent3'-four hours. These served as controls. Equal 

 amounts of blood and tissue were treated in the same manner, except that 

 the distilled water was substituted by a 1/20% solution of selenium acid 

 or a 1/10% solution of a selenium salt. After the extraction period a 

 definite volume of the filtrate was treated with 5 c. c. Oakland dioxygen 

 and the catalytic powers of the filtrate as measured by the volume of 

 oxygen evolved, determined for every thirty seconds. The liver, kidney 

 and blood showed the greatest catalytic activity. 



The compounds of selenium investigated had a marked inhibitory 

 effect on catalytic activity. Thus ten grams defibrinated blood evolved 

 52 c. c. oxygen in 7 minutes, another sample of the same l^lood treated 

 with 0.05% selenium dioxid evolved 49.8 c. c. in 21 minutes, a third 

 sample of the blood treated with 0.05% selenic acid evolved 52.6 c. c. in 

 14 minutes. 



Blood from another dog yielded 44.8 c. c. in 9 minutes, another sample 

 of the same blood treated with 0.1% potassium selenocyanate evolved 

 37.7 c. c. in 22 minutes. Control liver extract yielded 52.7 c. c. in 2 

 minutes; selenited liver extract yielded 50.2 c. c. in 8.5 minutes; selenated 

 liver extract, 49 c. c. in 4 minutes. Another control liver gave 45.5 c. c. 

 in 5.5 minutes, while another sample of the liver treated with potassium 

 selenocyanate yielded 41.7 c. c. in 13.5 minutes. Generally speaking, 

 the blood, liver, kidney, lung and spleen showed marked decrease in 

 catalytic activity, the decrease sometimes being as much as 60% or over. 

 Compared on the basis of equipercentages, it was found that selenium 

 dioxid was more harmful than selenic acid, and that sodium selenite 

 produced greater inhibition than sodium selenate. It is interesting to 

 note, however, that colloidal selenium (prepared by the reduction of 

 sodium selenite by glucose) brought about a slight acceleration in catalase 

 activity. 



