OXIDASES 113 



cleavage and oxidation until they arrive at the final 

 stage of metabolism. 



According to Traube,* we have to deal in the first 

 place with the splitting of water into H and OH ions. 

 The OH ion combines with and oxidises the oxi- 

 disable substance ; while the H ion combines with 

 neutral oxygen to form peroxide of hydrogen ; the 

 latter again having an oxidising action. It is known 

 that H and OH ions are toxic to cellular tissues, and 

 it is affirmed by Loew that certain cellular enzymes 

 which he calls catalases protect the cell from the 

 effects of these ions. 



The above supposes a direct oxidation of the 

 primary active substance. Animal oxidations may 

 however be brought about by oxygen-carriers, or 

 bodies which, without being oxidised themselves, 

 alternately take up and introduce oxygen into sub- 

 stances which are oxidised with difficulty or dys- 

 oxidisable. These were called by Traube oxidation 

 ferments and later oxidases. Little is known about 

 the nature or action of ferments. Some however 

 are nucleo-proteids, others, like the catalases, are 

 proteoses, while, on the contrary, liver-aldehyde and 

 laccase are not of a proteid nature. Some are direct 

 oxidases, others are indirect or peri-oxidases. They 

 seem to have a pronounced specific action, or as 

 Ehrlich calls it monotropism, that is to say, they oxi- 

 dise certain substances and not others. Their action 

 is not well understood, but it is a catalysis, produced 

 by intermediate reactions. Some of these oxidases 

 contain iron or manganese, and as these salts are 



* Hammarsten's " Physiological Chemistry," p. 6 (American 

 Edition). 



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