138 
THE FUNCTION AND NATURE OF CATALASE. 
Very little is known regarding the function of catalase or of its 
mode of action on hydrogen peroxide. We have seen that according 
to Schoenbein’s theory of oxygen-activation the inactive oxygen of 
the air is decomposed during processes of autoxidation, the negatively 
polarized -atom uniting with molecular oxygen to form ozone and the 
positively polarized atom combining with water to form hydrogen 
peroxide (an antozonide), and, further, that through the action of cer- 
tain carriers, such as finely divided platinum and the red coloring 
matter of the blood and what are now known as the peroxidases, the 
relatively inactive oxygen of the hydrogen peroxide is ozonized. 
This ozonized product can then accomplish the oxidation of easily 
oxidizable substances, such as guaiacum, etc., or it can react with 
another portion of the hydrogen peroxide, forming water and molecular 
oxygen after the manner of ozone itself, or of an ozonide, such as lead 
peroxide. In other words, the catalysis of hydrogen peroxide was of 
the nature of a secondary process in the sequence of changes occurring 
in the formation of ozone and ozonides as the result of the autoxida- 
' 
tion of easily oxidizable substances. The occurrence of catalase in 
the organic world is, according to Loew, too general and widespread 
to be accidental, and hence the enzyme must have, a certain signifi- 
cance. In considering its possible significance he pointed out that 
hydrogen peroxide results as either a primary or secondary product 
in the aut oxidation of many readily oxidizable organic substances. 
Hence he regarded it as conceivable at least, that hydrogen peroxide 
might also be produced in the living cell as the result of the respira- 
tory process. The accumulation of such a substance as hydrogen 
peroxide would undoubtedly prove harmful to the life of the organ- 
ism, and hence he conceived the function of catalase to be to destroy 
the hydrogen peroxide as fast as formed. The ferment would thus 
afford an important protection against the accumulation of this poi- 
sonous substance, and the oxygen thus liberated could be again 
utilized for a continuance of the respiratory process. He also ad- 
vanced the idea that just as catalase loosens the affinities of oxygen 
in hydrogen peroxide, so also it might loosen the affinities in certain 
other compounds, as the result of which they might be more easily 
decomposed or oxidized by the protoplasm. 
Herlitzka ( 209 ) has found that within certain limits the greater the 
concentration of catalase the greater the concentration of peroxidase 
required to produce oxidation. This points to a protective action 
on the part of catalase against the peroxides of the organism. 
Shaffer ( 401 ) is also of the opinion that through the decomposition of 
hydrogen peroxide by catalase into water and molecular (inactive) 
oxygen, the tissues are protected against injurious oxidation. In 
