1904.] Studies on Enzyme Action. 211 



Mercuric salts are energetic poisons for both higher and lower 

 organisms.* Paul and Kronigf have shown that the poisonous 

 action on bacteria diminishes from the chloride through the bromide 

 to the cyanide, and it is known that the electrolytic dissociation 

 decreases in the same order. 



Mercuric chloride in the amount of one-millionth paralyses the 

 action of diastase on starch \ and, according to Bredig, is a very 

 active poison for the platinum catalysis of hydrogen peroxide. 



From the quantitative measurements given above it is clear that 

 mercuric chloride is about five times as toxic as mercuric bromide towards 

 the hsemase catalysis, || and at least 20,000 times as toxic as mercuric 

 cyanide. 



Effect of some other Poisons on the Reaction. 



Carbon monoxide. As is well known, carbon monoxide is very 

 poisonous towards the higher animals on account of its property 

 of forming a stable compound with the haemoglobin of the blood. 

 It was therefore a matter of interest to investigate its effect on the 

 enzyme-catalysis of hydrogen peroxide, since the enzyme used is got 

 from blood. 



In order to get as much of the gas as possible dissolved, measure- 

 ments were carried out at ; the gas was passed through a dilute 

 solution of the enzyme in a bottle for 4 minutes, then, without stopping 

 the current, the hydrogen peroxide was added and the stopper inserted, 

 the bottle being thus filled with an atmosphere of the gas. 



It was found that the gas exerted no appreciable poisoning effect ; 

 the constant in the presence of CO was 0*0085, and in its absence 

 0*0090, an agreement with the limit of experimental error. 



Carbon monoxide is not poisonous towards the germination of seeds,U 

 nor towards bacteria ;1T according to Buchner,** it does not affect the 

 fermentation of sugar by zymase. It retards the catalysis of hydrogen 

 peroxide by colloidal platinum. ft 



Iodine. Iodine, as well as bromine and chlorine, are poisonous for 

 all living matter,!! and Bredig, in his interesting experiments on the 



* Loew, ' Die Giftwirkungen,' p. 35. 



t ' Zeit. f. physik. Chemie,' rol. 21, p. 414 (1896). 



I Effront, loc. tit., p. 116. 



Bredig, loc. cit., p. 81. 



I! Up to the present the extent to which, solutions of mercuric bromide are 

 hydrolysed is not known, so that the relative ion concentrations of these solutions 

 cannot be calculated, vide Luther, ' Zeit. phys. Chem.,'vol. 47, p. 107 (1904). 



*T Loew, loc. cit., p. 103. 



** See Ikeda, 'Zeit. physik. Chemie,' vol. 37, p. 26 (1901). 



ft Bredig, loc. cit., p. 78; 



Loew, loc. cit., p. 16. 



Bredig, loc. cit., p. 74 



