13 
TWO KINDS OF CATALASE. 
It was one of the first observations of the writer when he com- 
menced the study of the new enzym that it existed in aninsoluble and 
in a soluble form. These may be distinguished as a- and /-catalase, 
respectively. The former is probably a compound of the soluble cat- 
alase with a nucleo-proteid, while the soluble catalase is an albumose 
and can be liberated by the action of very dilute alkaline media upon 
the insoluble catalase. This conversion can be observed well in the 
process of sweating tobacco in bulk, whereby the temperature grad- 
ually reaches 60° C., and ammonium carbonate is generated as one of 
the products of the destructive processes going on. Cured tobacco 
contains but little soluble catalase, while well-sweated tobacco contains 
much. For example, it was observed that the cold-prepared aqueous 
extract of 2 grams of cured tobacco yielded in thirty minutes, on the 
addition of dilute hydrogen peroxid in excess, only 16.5 cc. of oxygen, 
while the same tobacco after’ sweating in bulk yielded 236 cc. under 
similar conditions. 
Sometimes sweated tobacco proves rich in /-catalase, as may be 
inferred from the following test. Five grams of finely powdered 
tobacco (Zimmer Spanish) were digested for twenty-four hours with 
500 cc. of cold water, with the addition of some chloroform. Twenty 
ec. of this highly diluted extract yielded in that hy minutes, upon the 
addition of 5 cc. hydrogen peroxid, 34 cc. oxygen.’ 
Crude /-catalase is obtained by preparing at the ordinary tempera- 
ture a concentrated extract from tobacco sweated in bulk, with water 
containing chloroform, using the same water for extracting three or 
four portions of the tobacco. This extract is saturated at the ordi- 
nary temperature with ammonium sulphate. The precipitate thus 
obtained is dried at the room temperature between sheets of filter 
paper, which removes most of the adhering salt solution. This crude 
product contains, among other substances, besides adhering ammonium 
sulphate, a brown coloring matter which can not be removed by digest- 
ing the solution with boneblack, since this absorbs the dissolved enzym 
also. The ammonium sulphate can be removed by osmosis, and the 
enzym may then be precipitated by alcohol. The activity is better 
preserved, however, when the fresh moist precipitate is dissolved in 
some glycerol. Colorless products can be prepared from the seeds of 
clover or poppy; but these preparations are weaker than that from 
sweated tobacco, since they contain more impurities, among which - 
may be found a little peroxidase. A very energetic product may be 
‘The hydrogen peroxid preparation mentioned in this bulletin refers to the com- 
mercial article. It contained from 2.8 to 3.1 per cent pure hydrogen peroxid. The 
weak acid reaction was removed immediately before use by diluted sodium hydrate 
or carbonate. A preparation one am 1 m es its volume of oxygen by catalysis 
contains 3.04 per cent of _— peroxir 
cease is vege | , 
