1910] APPLEMAN—CATALASE 183 
Since the decomposition of hydrogen peroxid is the most 
important property of this powerful enzyme so widely distributed, 
it was suggested by Loew that it may possess the function of 
preventing the accumulation of this toxic substance in the tissues. 
He conceived it possible and highly probable that hydrogen peroxid 
was produced in the living cells as the result of respiratory pro- 
cesses. USHER and Prigstiy (9g) were able to demonstrate the 
presence of hydrogen peroxid during photosynthesis if the catalase 
were previously destroyed. This fact would seem to support the 
above theory, but on the other hand, BAcH and CuHopat (2) have 
shown that hydrogen peroxid is not a violent poison in tissues, 
since they have been able to cultivate certain plants in a medium 
containing 0.68 per cent of it. Catalase is found also in anaerobic 
organisms, a further fact which rendered the above conception 
untenable. Other authors have ascribed to catalase the function 
of protection against the peroxids of the organism, thus preventing 
injurious oxidations. It is unable, however, to decompose the 
substituted organic peroxids, such as ethyl hydroperoxid or the 
oxygenases (2). 
Probably the most important question in connection with 
catalase at the present time is whether or not it may be considered 
as an oxidizing enzyme. It is true that it does not respond to the 
tests with the ordinary reagents for oxidizing enzymes, but this, 
according to Loew, does not militate against its being an oxidizing 
enzyme, since the action of oxidizing enzymes is sometimes quite 
specific. He claims that a characteristic oxidation by catalase is 
produced with hydroquinone and also some with glucose and citric 
acid. SHAFFER (3) thinks that this quinone-formation was 
undoubtedly due to the presence of some enzyme other than 
catalase, since he found that animal tissues always contain catalase, 
but frequently possess no power to oxidize hydroquinone. 
According to the BucHNER and MEISENHEIMER (4) conception 
of alcoholic fermentation, the sugar is converted into lactic acid 
by the zymase, and the lactic acid in turn is split up into 
alcohol and carbon dioxid by a lactacidase enzyme. In a recent 
work Koni (5) claims to have proved, for yeast fermentation at 
: least, that catalase performs the function of the zymase in the above 
ra 
