20 
BEHAVIOR TOWARD VARIOUS SALTS. 
A careful distinction should be made here between the relation of a 
salt to the enzym itself and the influence of a salt upon its activity 
alone. ‘This activity can be stimulated or retarded without the enzym 
itself being changed in its chemical nature. Salts of a strong acid or 
alkaline reaction will of course injure the enzym itself, while salts of 
neutral reaction will probably not do so. Thus, a-catalase is not injured 
in one day by a LO per cent solution of magnesium sulphate, nor in five 
hours by a 5 per cent solution of sodium sulphate, nor in twenty hours 
by a 2 per cent solution of potassium persulphate,' nor in one day by 
a saturated solution of ammonium sulphate. After these salts are 
removed by careful washing the a-catalase contained in sweated tobacco 
is found fully preserved, or very nearly so. It is véry probable that 
f-catalase is more easily injured, but nevertheless it can even be salted 
out by saturation of its solution with ammonium sulphate without 
immediate loss of power, although the subsequent drying at the ordi- 
nary temperature with the adhering salt leads to a partial loss of its 
activity. 
A concentrated extract was prepared at the ordinary temperature 
from sweated tobacco (Connecticut crop of 1899) rich in @- and /-cata- 
lase, and containing no oxidase and only a trace of peroxidase. Ten 
cc. of this extract were mixed with 20 cc. of hydrogen peroxid (added 
in two doses), and in five minutes 160 cc. of oxygen were developed. 
By saturation with ammonium sulphate a brown-colored precipitate of 
great catalytic energy was obtained, while the filtrate showed only 
a trace of activity. After being collected on a filter and dried for 
twenty-four hours at the ordinary temperature on a porous plate, the 
precipitate weighed 2.85 grams, more than half of which, however, 
consisted of adhering ammonium sulphate. Half a gram of this 
powder dissolved in 20 ec. of water in five minutes developed 223 ce. 
oxygen, and in fifteen minutes 449 cc.” 
The considerable depression of the catalytic activity of /-catalase 
by nitrates is very remarkable. The enzym itself does not seem to be 
injured materially, as several tests have shown. For example, a very 
small quantity of a £-catalase preparation, obtained by salting out a 
cold-prepared concentrated tobacco extract with ammonium sulphate, 
was kept ina 10 per cent solution of potassium nitrate for twenty- 
1It might be supposed that this salt would exert an oxidizing action detrimental to 
the enzym, but such indifferent behavior of the salt has been noticed in other cases 
also; for example, toward certain aniline colors. (Proscher, Chem.-Zeitung, March, 
1900.) Potassium persulphate easily oxidizes hydroquinone to quinone, @-naphthyl- 
amine to the blue oxynaphthylamine, and behaves in its oxidizing property like 
ferric chlorid. ; 
* The observation of Jacobson that the ‘‘catalytic power’’ of a pancreas extract, 
or of an emulsion of almonds, is lost by saturation with sodium sulphate, is probably 
due to his drying the salted-out product at a higher temperature. 
