57 



Oxidases," it appears that oxygenases of certain fungi are ex- 

 tremely resistant to the influence of both heat and long standing. 

 In the case of the oxygenase from Lepiota americana, it was 

 necessary to heat for several minutes to a' temperature of about 

 85° in order to destroy the power of the extract to blue 

 guaiacum directly. Still more striking is the case of the glycerin 

 extracts of certain Lactarius spp., which after standing from 1905 

 to 1909 were found to be still active towards ^both guaiacum 

 and tyrosin. It is interesting to note that of the many species 

 of the higher fungi which Kastle tested, only one, Amanita 

 verna, did not show any response for the oxidases. This p'ant 

 is so poisonous that it has been called the "destroying angel." 



From all the experimental work of the different investigators 

 it seems probable that peroxidase is an enzyme rather than a 

 simple catalyzer. Little is really known of the nature of peroxi- 

 dase. Bach^^ has prepared a powerful peroxidase which gave 

 no tests for proteins, nor did it contain iron or manganese. 

 On the other hand. Van der Haar^^ claims his Hedera oxidase 

 was a glucoprotein. Resistance to heat seems to be a peculiarity 

 of peroxidase. Heating to boiling is necessary to destroy peroxi- 

 dase, while oxygenase is destroyed at a much lower temperature. 

 Bach and Chodat noted this fact and also that upon standing 

 after boiling, the peroxidase regained its activity. Woods-" first 

 discovered, this phenomenon while studying the peroxidase of 

 the tobacco leaf, and concluded that in these cases we are dealing 

 with a zymogen or a substance which regenerates the peroxidase 

 upon standing. Aso^^ also found that there were zymogens more 

 stable towards heat than peroxidase itself, which slowly yielded 

 more of the latter after the destruction of the initial supply. A 

 second heating permanently destroys the peroxidase ; the stronger 

 the solution of the enzyme, the more resistant it is towards heat. 



18 Bach. Zur Theorie der Oxydasenwirkung: I. Mangan und eisenfreie Oxydasen. 

 Ber. Chem. Gesell. 43: 364. 1910. 



I'Van der Haar. Untersuchungen in Pflanzenoxydasen: II. Die Hederaper- 

 oxydase, ein Glucoproteide. Ber. Chem. Gesell. 43: 1321. 1910. 



2" Woods. The Mosaic Disease of Tobacco. Report No. 18 [p. 17], U. S. Dept. 

 Agric. 1902. 



2'Aso. Which Compound Can Liberate Iodine from Potassium Iodide? Bei- 

 hefte z. Botan. Centralblt. 15: 208. 1903. 



