39 



Chodat and Bach 56 prepared peroxydase from cucumbers and 

 horseradish but on account of the large amount of water in the 

 former, they preferred to prepare it from the horseradish as the 

 yield was much larger. Their method was to reduce it to as fine 

 a condition as possible and allow it to stand for an hour to permit 

 the glucoside-splitting enzyme to act, then to express the juice 

 and precipitate with absolute alcohol. The precipitate was ex- 

 tracted with 40% alcohol, the alcoholic solution concentrated in 

 a vacuum at 30 C. and precipitated with absolute alcohol and 

 dried in a vacuum. 



The product is a yellowish gummy mass which in solution 

 reduces Fehling's solution ; however they claim that this is not 

 due to the enzyme, for by repeated precipitation an enzyme may 

 be obtained which will not reduce Fehling's solution. 

 The purest peroxydase obtained from horseradish con- 

 tained 6 per cent, of ash of which aluminum amounted 

 to 0.8 to 1.4 per cent, and manganese from 0.2 to 0.6 per cent. 

 They found that the peroxydase from Russule and Lactar- 

 ius was much more active than that from the horseradish or 

 cucumber ; on the other hand with hydrogen peroxide the activity 

 was reversed. By heating a mixture of oxydase and peroxydase 

 to 70 C. the former is destroyed while the latter is only weaken- 

 ed but seems to regain its strength on standing" but if subjected 

 to a second heating its activity is destroyed completely. In alco- 

 holic solution it is destroyed by boiling. Peroxydase does not 

 possess the power to oxidize except in the presence of peroxides. 

 The same authors state 08 that peroxydase and catalase 

 are present in nearly all parts of plant and animal 

 bodies, and apparently are antagonistic, as the first is 

 active with hydrogen peroxide while the other is destroyed 

 by oxygen. They experimented upon a mixture of oxygenase, 

 peroxydase and pyrogallol alone, and in the presence of catalase, 

 and found that catalase had no effect upon the amount of oxygen 

 absorbed. In another experiment catalase was mixed with oxy- 

 genase and peroxydase, and the mixture allowed to stand over 

 night, then hydrogen peroxide was added and the amount of gas 

 liberated was found to be the same as without the catalase. Hence 



M Ber. d. Chem. 36, 1903, p. 600. 



57 Compare U. S. Dept. of Agric., Bull. No. 8, 17. 



BS Ber. d, Chem. 36, 1903, p. 1756. 



