20 
paper, the precipitate was easily dissolved in water. This solution not 
only gave intense reactions for oxidase and peroxidase, but yielded also 
a precipitate with alcohol and gave Millon’s reaction; the biuret reac- 
tion, however, was impeded by the dark color of the liquid. Both 
oxidase and peroxidase, therefore, seem to have the main character of 
aibumoses. It follows, then, that the animal oxidase must differ from 
the vegetal, since Abelous and Biarneés believe the former to be a kind 
of globulin.' When the aqueous extract of dried tobacco leaves’ is 
neutralized, a small amount of precipitate is obtained, containing, among 
other things, lime salts, and a part of the oxidase mechanically carried 
down. 
BEHAVIOR OF OXIDIZING ENZYMS TOWARD INJURIOUS COMPOUNDS. 
The supposition might be entertained that oxidase and peroxidase 
are chemically closely related, the latter representing, perhaps, a deriva- 
tive of the former. Peroxidase, however, resists not only a higher 
degree of heat than oxidase, but also is less easily injured by poisons. 
in comparing tobacco oxidase with tobacco peroxidase in their 
behavior toward noxious compounds, a solution of the former was pre- 
pared in the manner formerly described,’ and its reaction compared 
with the oxidase reaction in fresh tobacco juice after addition of various 
soiutions of known strength.’ Before making the tests care was taken 
to have a neutral or only slightly acid reaction, as guaiac blue is easily 
altered by various influences, and especially by mineral acids and alka- 
lies. Also, certain organic substances of comparatively weak acid 
qualities, like tannin, can prevent the reaction. Acetic acid, in higher 
concentration than 2 per cent, interferes with the production of the 
guaiac blue. 
The following table sige the results obtained: 
Reagent. | Oxidase. Peroxidase. 
Acetic acid, 3 per cent-.-..-..- Killed within 5 hours....--- Reaction much weaker after 24 hours. 
Acetic acid, 1 per cent..----.- | Killed within 24 hours..---. _ Reaction weaker after 24 hours. 
Hydr ochloric acid, 6.5 per | Killed immediately -...-..--.| | Killed immediately. 
cent. | 
Sulphur dioxide, 0.25 per |-.---. dO: 228 Jak Se ees ee Unchanged after 24 hours. 
cent. | 
Ammonia, 0.3 per centa..--. But little altered after 24 | Unaltered after 48 hours. 
hours. 
Potassium hydroxide, 0.3 per | Con siderably decrease d| Do. 
cent. a | after 2 days. | 
Free nicotine, 1 per cent ..--- | Killed in 24hours-.--:...--- | Do. 
Formaldehyde, 5 per cent.--.|.-...- COS eae erate ee one: Do. 
aIn these cases the fresh juice was neutralized before adding the above percentage. 
‘Compt. Rend. Soc. Biol., vol. 49, p. 493. 
* Report No. 59, U.S. Department of Agriculture, p. 29. 
3A colorless solution of the tobacco oxidases can not be obtained from the lamina 
of the tobacco leaves, since the juice turns brown very soon, but it may be obtained 
from the midrib by grinding it, expressing the pulp, and filtering the liquid. By 
heating a moment to 65° C. (149° F.), the albuminous matters coagulate and a clear, 
colorless filtrate is obtained which turns yellow but slowly. 
