BY MEANS OF CATALYSTS. CREJGHTON. 



31 



poisons. The poisoiiious influence of inany substances towards 

 inorganic catalysts has been thoroughly investigated by Bredig 

 and his pupils in the last few years. The effect of a number of 

 different poisons on inorganic catalysts and enzymes is illus- 

 trated in the accompaning table, in which is shown the con- 

 centration of the different poisons that is necessary to entirely 

 destroy the catalytic influence of colloidal platinum^ and of 

 catalase" on hydrogen peroxide: 



Poison 



Colloidal Platiiunu 



Catalase 



H.,S 



1 : 800 000 molar 





1 000 000 molar 



HCN 



1 



20 000 000 '• 

 2 000 000 " 





1 000 000 " 



HgCl, 



2 000 000 " 



Hg(CN), 





■ 200 000 " 





800 " 



I in KI 





5 000 000 " 





50 000 " 



NH,(0H)HC1 ... 



- 



25 000 " 





80 000 " 



Aniline 





5 000 '■' 





40 000 " 



As^O 





50 " 





2 000 " 



CO ... 



ver}' poisonous 





no paralysis 



HCl 



1 : 8 000 molar 





100 000 " 



NH^Cl 



1 : 2 000 " 





1 000 •■' 



HNO3 





no pai-alysift 





250 000 " 



That enzymes exhibit a stereochemical specificity has long 

 been known. The princij^le here involved is that one of the 

 antipodes of the substrate is changed much quicker by the 

 enzyme than the other, which very often remains practically 

 unchanged. Pasteur^ observed, for instance, that with racemic 

 ammonium tartrate only the idextro antipode was attacked by 

 mould enzyme (penicillium glaucum), the solution becoming 

 laevo-rotatary. Our fundamental knowledge in this field, how- 

 ever, is due to the researches of E. Fischer. He has showm 

 that a particular enzyme is able to attack certain stereochemical 



1. Bredig-. G., and MiiUer v. Berneck: . Zeit. f. phys. Chem., 31, 25S, 

 (1899). 



2. Senter, G.: Zeit. f. pliys. Chem., 44, 257, (1903). 



3. Pasteur: Compt. rend., 51, 298, (1860). 



