56 



the original oxidizing substance as present in the plant. This 

 research was the beginning of, a series of notable contributions to 

 our knowledge of the oxidizing enzymes. In another paper, 

 these authors state that peroxidase is present in nearly every plant . 

 They were able to prepare a pure peroxidase from the horse- 

 radish root, which exhibited great stability towards heat. In 

 further comparative studies they showed that peroxidase great y 

 augments the power of the natural oxidases, especially that oxy- 

 genase from the same source as the peroxidase itself. All of 

 these observations led Bach and Chodat to separate oxidases into 

 two parts, the organic peroxide part, which they called "oxyge- 

 nase" and the activator of oxygenase and other peroxides, to 

 which alone they gave the name "peroxidase." 



Kastle and Loevenhart^^ in 1901 published a very important 

 paper which has not always received due attention from the 

 European chemists engaged in this work. These authors found 

 that the substance bluing guaiacum directly is easily precipitated 

 by alcohol and is destroyed by small amounts of hydrocyanic 

 acid, hydroxyl amine and phenyl hydrazine. It seemed peculiar 

 to them that these substances should be so harmful, but that 

 sodium hyposulphite, silver nitrate and mercuric chloride, sub- 

 stances usually fatal to enzymes, should exert little effect on the 

 constituent of the potato which blues guaiacum directly. In 

 general, those substances which prevented the direct bluing of 

 guaiac tincture by the potato juice also prevented similar action 

 upon guaiacum by the organic and inorganic peroxides with 

 which they experimented. All of these experiments caused them 

 to believe that this direct bluing was not due to enzymes at all, 

 but to organic peroxides which were formed when the juice is 

 exposed to the air, according to Engler's theories of auto-oxida- 

 tion. Thus we see, the idea that oxidases are made up of an 

 organic peroxide part activated by the enzyme peroxidase receives 

 further confirmation from this work of Kastle and Loevenhart. 



In a valuable paper by Kastle^^ on "The Stability of the 



1^ Kastle and Loevenhart. On the Nature of Certain Oxidizing Ferments. 

 Amer. Chem. Jour. 26: 539. 1901. 



"Kastle. On the Stability of the Oxidases, etc. Bull. 26, Hyg. Lab. U. S. 

 Pub. Health and Mar. Hosp. Serv. Washington, 1906. 



