OXIDIZING ENZYMES ()3 



OXIDIZING ENZYMES" 



Although oxidation of organic compounds is the chief sour(;c of 

 energy in the animal body, yet the way in which it is accomplished 

 is very little understood. We only know that it is brought about 

 within the cells, and that substances that outside the body are oxidized 

 with difficulty, are completely oxidized to car})on dioxide and water 

 within the cells, and that this is done with just such a degree of rapid- 

 ity that the heat produced is in exactly the amount necessary for 

 the wants of the bod3^ There can be little question that this oxida- 

 tion is accomplished through catalytic agents acting within the cells, 

 and certain of them have been placed in a condition permitting of 

 study. As yet their exact relations to intracellular oxidation are 

 not clearly defined, but for the present they may be grouped pro- 

 visionally as oxidizing enzymes. That some of them arc highly specific 

 is shown by those disorders, such as alkaptonuria and diabetes, in 

 which the body loses the power to oxidize a certain chemical substance 

 while retaining the normal power to oxidize innumerable other sub- 

 stances. According to Lillie^^ the oxidative processes in cells take 

 place most actively in relation to the membrane surfaces (or phase 

 boundaries) of the cells. Of the oxidizing enzymes as yet identified 

 none can be considered as of importance in the energy-producing 

 oxidations of the body (Battelli and Stern), all the enzymes of this 

 class yet known being apparently concerned with less essential oxidiz- 

 ing processes; it is indeed possible that the essential oxidation of 

 food-stuffs ma}^ not be dependent on enz3'mes (Engler and Herzog).^^ 

 An agent accelerating the essential oxidizing activities of the tissues 

 has been described by Battelli and Stern' under the name of pnein, and 

 an anti-pneumin which holds it in check. Closely related to the oxidiz- 

 ing enzj^mes is — • 



Catalase. — It has long been known that most enzymes possess 

 the power of decomposing hydrogen peroxide, with liberation of 

 oxygen; but it was not until 1901 that it was finally demonstrated by 

 Loew that this property was due to a separate enzyme and was inde- 

 pendent of the specific properties of the various other enzymes. This 

 ferment is very wide-spread, and so is generally obtained along with 

 the other enzymes when attempts are made to isolate them from the 

 cell. It was named catalase by Loew, and he described two forms, a- 



9^ Complete bibliography and exhaustive discussion by Kastle, Bull. Hygienic 

 Lab.,- No. 59; by Loele, Ergeb. allg. Path., 1912 (16, Pt. 2), 760; and by BattelU 

 and Stern, Ergebnisse d. Phj-siol., 1912 (12), 96. Concerning the chemistry of 

 vital oxidations see Dakin, "Oxidations and Reductions in the Animal Body," 

 Monographs on Biochemistry, London, 1912. Good review by v. Fiirth. "Chem- 

 istry of Metabolism," Chaps. 22 and 23; translated by A. J. Smith, Philadelphia, 

 1916. 



38 Jour. Biol. Chem., 1913 (15), 237. 



93 Zeit. phvsiol. Chem., 1909 ^59), 327. 

 iBiochem. Zeit., 1911 (33), 315; 1911 (36), 114. 



