Catalase. 47 



by abstracting active oxygen after the formula H 2 2 =H 2 0+0 

 (Jensen). The active oxygen oxidizes the added "chromogenic" 

 substances, as guaiacol, ursol, paraphenylendiamin, etc., to coloring 

 matter. The peroxydase is injured by long heating, even at the 

 relatively lower temperature (50-60-70 deg. C.), and is destroyed 

 at about 75 deg., so that boiled or pasteurized milk may be dis- 

 tinguished from raw milk by the non-appearance of the color 

 reaction. 



The action of the superoxydase (Raudnitz) or catalase 

 (Loew) develops in a different way. It splits the H 2 2 according 

 to the formula 2 H 2 2 =2 H 2 0+20, which join to a molecule of 2 . 

 Other authors include the superoxydase with the oxidizing fer- 

 ments, as the freed oxygen is utilized in the body for the oxidation 

 (Seligmann). According to others it is included with reductase, 

 as the action of the ferments on H 2 2 equals a reduction of 2 H 2 0, 

 and molecular oxygen 2 which passes out without being utilized 

 for oxidation, whereas the oxygen freed by peroxydase is imme- 

 diately utilized for further oxidation changes; therefore the per- 

 oxydase is an oxidyzing, while the catalase is a reducing ferment 

 (Grimmer). 



Original catalase has been demonstrated in the milk of all 

 animals ; it originates in the cells of the milk gland, especially from 

 the leucocytes. It is secreted, but may be set free in the breaking 

 down of cells or may appear bound to the cell. That catalase is 

 derived from the cells (especially leucocytes) is not contradicted 

 by the fact that cream is richer in catalase than skim milk since 

 leucocytes and other cells are also included in the separation of 

 the cream. These conditions were indicated by Friedjung, Hecht 

 and Pallazzi, and later confirmed by Koning. This also explains 

 the reason for the centrifuge foam, rich in leucocytes, giving such a 

 strong reaction. Since the formed elements (cells) are precipitated 

 with the casein, and probably a part of the free ferment is also 

 drawn down with it, milk serum is always poorer in catalase than 

 the original milk. 



Catalase passes through infusorial earth filters, but consider- 

 able quantities are retained. Light, storage, etc., affect catalase, 

 even if it is relatively resistant. A leucocytic extract, which was 

 kept exposed to the light in the laboratory of the author, showed 

 even after months, an unweakened action to H 2 2 , while hydrogen 

 sulphide, hydrocyanic acid, potassium cyanide, mercuric cyanide, 

 barium nitrate, hydrochloric acid, sulphuric acid, acetic acid, 

 oxalic acid, and potassium nitrate affected its action (Faitelowitz). 

 It appears noteworthy that H 2 2 inhibits the ferment in its action. 

 In the presence of excessive amounts of peroxide of hydrogen the 

 ferment splits up less H 2 2 than if the diluted peroxide of hydro- 

 gen is gradually added. 



Heating to 62-70 C. destroys the original catalase in a short 

 time. The optimum temperature appears to be about 37 deg. C. 



