548 OXIDATION FERMENTS 



Dony-Henault 30 obtained peroxidase-like products by mix- 

 ing bloodserum or a mucilage with weak alkaline reaction 

 with a salt of manganese and precipitating with alcohol, 

 adding Eochelle salt as a suitable material to prevent the 

 separation of manganese oxide. Euler and Bolin 31 found 

 a typical peroxidase prepared from alfalfa to be thermosta- 

 ble and certainly not an enzyme, but rather a mixture of 

 neutral salts (especially potassium salts) of various vege- 

 table acids (as citric acid, malic acid and mesoxalic acid), 

 and that such salts are capable in plant structures and juices 

 containing manganese of catalytically accelerating the oxida- 

 tion of polyphenols, etc. According to J. Wolff 32 if yellow 

 ferrocyanide of potassium be mixed in certain porportions 

 with ferrous sulphate, blue colloidal ferrous ferrocyanide 

 will be obtained. This substance behaves quite like a per- 

 oxidase and is thermolabile. The oxidases seemed to be 

 peculiar in the specificity of their action (as, for example, a 

 tyrosinase may fail to act upon hydrochinon). However, it 

 has been found that artificial colloids may also manifest 

 similar specificity. Thus iron in the presence of dibasic 

 phosphate produces an oxidation of hydrochinon, but re- 

 mains inactive if the phosphate is replaced by tribasic 

 citrate. 



Doubt as to the Ferment Character of Peroxidases. 

 These and similar observations necessarily arouse serious 

 doubts as to the enzymic nature of peroxidases. Bertrand 33 

 regards the sensitiveness of a number of peroxidases, par- 

 ticularly the "laccases," toward acids as supporting his 

 view of the role played by metals in oxidase- activity. If, 



80 O. Dony-H6nault (Instit. Solvay, Brussels), Bull. Acad. roy. de Belgique, 

 1907, 1908, 1909. 



M H. Euler and J. Bolin (Stockholm), Zeitschr. f. physiol. Chem., 57, 80, 

 1908; 61, 72, 1909. 



33 J. Wolff, numerous papers in Compt. rend, and in C. R. Soc. de Biol., 1908, 

 1909; partly in association with E. de Stocklin; also Thesis, Paris, 1910, and 

 Ann. Instit. Pasteur, 23, 841, 1909; 24, 789, 1910. 



88 G. Bertrand, Ann. Instit. Pasteur, 21, 673, 1907. 



