78 ENZYMES 



expressed from tubercle bacilli by Hahn. Loewenstein l found 

 an enzyme agreeing with catalase in filtered bouillon cultures 

 of diphtheria bacilli and staphylococci but not from tetanus, 

 typhoid, and colon bacilli or cholera vibrios ; the catalase is 

 quite distinct from the toxin. He also found that the addition 

 of H 2 O 2 to a diphtheria toxin-antitoxin mixture destroyed the 

 toxin, leaving the antitoxin free. A similar destruction of 

 tetanus toxin by peroxides, first demonstrated by Sieber, can 

 occur without the catalase. 



True Oxidising Enzymes. While it is by no means cer- 

 tain that catalase is active in causing intracellular oxidations, 

 there are a number of other enzymes or enzyme-like substances 

 that come more properly under the head of oxidases or oxidizing 

 enzyme. Those so far studied are : 



Peroxidase. This name is given to an enzyme that is be- 

 lieved to cause oxidation by activating peroxides, and is quite 

 distinct from catalase and from the other oxidases. The peroxide 

 on which they chiefly act in the cell is supposed by Bach and 

 Chodat 2 to be the enzyme oxygenase. 



Oxygenase. This enzyme can also act as an oxidizer in- 

 dependent of the peroxidase, in the presence of certain manganese 

 compounds. Loevenhart and Kastle 3 question the true enzyme 

 nature of this and other " oxidases," which they look upon as 

 organic peroxides, behaving like other peroxides rather than as 

 catalyzers. Practically the knowledge of these bodies is demon- 

 strated by their power to turn tincture of guaiac blue, and they 

 are, therefore, present in pus. 



By their conception of oxygenase and peroxidase Chodat and 

 Bach would displace entirely the idea of enzymes oxidizing 

 directly, the true " oxidases/ 7 which they consider mixtures of 

 oxygenase and peroxidase. How far this is justifiable may 

 well be questioned. There have been, in any event, a number 

 of ferments described that seem to possess distinct oxidative 

 powers. As each is quite specific in its action, oxidizing but 

 one substance, or one group of related substances, they are 

 generally designated by the name of the substances upon which 

 they act. Most studied of these is 



Aldehydase, which is characterized by. oxidizing aldehydes, 

 particularly salicyl-aldehyde. According to Jacquet, this enzyme 



1 Wien. klin. Woch., 1903 (16), 1393. 



2 Biochem. Centralblatt, 1903 (1), 417 and 457, where is also given a re'sume' 

 of the literature. 



3 Amer. Chera. Jour., 1903 (29), 563. 



