%OXIDASES 393 



63 according to Yoshida, and at 70 according to Bertrand. 

 Bertrand * also has given much attention to this oxidase, and 

 the most important fact ascertained by him^n this connexion 

 is that the presence of manganese is all-important. He found 

 that the activity of the ferment is directly proportional to the 

 amount of the metal present, which acts as a co-enzyme (p. 357). 

 But whether manganese is essential for all oxidase reactions 

 is uncertain, for Bach t states that he has prepared a tyrosinase 

 which will oxidize tyrosine in the absence of manganese and 

 of iron. . 



ISOLATION OF OXIDASES. 



The isolation of oxidase may be a difficult matter when it 

 exists in a tissue together with its substrate and other enzymes. 

 Bourquelot and Bertrand give the following method for Fungi 

 such as Russula. The tissue is chopped up, extracted with 

 water which may be warmed and filtered as quickly as may 

 be. The filtrate is then poured into an excess of strong 

 alcohol, whereby the enzyme is precipitated. The precipitate 

 is then filtered off and dissolved in water. 



When the oxidase is extracted together with other oxi- 

 dizing enzymes, separation may be effected, at any rate in part, 

 by adding to the aqueous solution of the oxidase, or to the 

 aqueous extract of the plant, two volumes of absolute alcohol 

 for each volume of extract. The oxidase will be precipitated, 

 whilst the other enzymes will remain in solution. J 



PEROXIDASE. 



Peroxidases which split oxygen from hydrogen peroxide, 

 organic peroxides, potassium permanganate, etc., are often 

 associated with other oxidases, and are very widely distributed ; 

 indeed, they have even been described as occurring in coal. 



According to Willstatter and Stoll,|| the peroxidase of the 

 horse-radish appears to be a nitrogenous glucoside containing 



* Bertrand: " Compt. rend.," 1895, 120,266; 1895, 121, 166; 1896, 122, 

 1132; 1896, 123, 463; 1897, 124, 1032, 1355. 



fBach: " Ber. deut. chem. Gesells.," 1910, 43, 362. 



tAso: "Bull. Coll. Agric. Imp. Univ., Tokyo," 1902, 5, 207. 



Stoklasa, Ernst, and Chocensky : " Ber. deut. hot. Gesells.," 1907, 25, 38. 



|| Willstatter and Stoll : " Annalen," 1918, 416, 21. 



