a ; 
r . 
J . 
1908. | Studies on Enzyme Action. 3 325 
On heating the extract at 45° during three hours it was entirely deprived 
of the power of hydrolysing milk-sugar ; it retained its activity as a hydrolyst 
of @-methylglucoside, amygdalin and salicin, however, not only after 
20 hours’ heating at 45°, but even when heated during several hours at 55° 
in presence of these hydrolytes; the enzyme was practically destroyed by 
heating at about 59°. 
The preparation obtained by macerating almonds with water at about 57° 
was found to be active towards the three glucosides at 38°, but when heated 
to 62° it became inactive. 
By macerating almonds with water at about 0° and then again macerating 
the extracted paste with a further quantity of water at 45°, extracts were 
obtained from which “emulsins” were prepared in the manner described. 
Both preparations hydrolysed milk-sugar at 38°; only that made at the 
lower temperature, however, produced perceptible hydrolysis at 15°—an 
indication that the gluco-lactase had been preferentially extracted at the 
lower temperature. 
Cane-sugar, maltose and 6-methylglucoside were not in the least affected 
by these preparations. 
A solution containing 5 per cent. of lactose was completely hydrolysed at 
38° in the course of a week, when presumably the enzyme was in equilibrium 
with the products of change; a volume of the sugar solution equal to that 
first taken was then added: it was found that hydrolysis took place as before 
and became complete, showing that the enzyme had retained its activity. 
Extracts prepared in the manner described, if maintained sterile by means of 
toluene, have been found to retain their activity almost unchanged during 
many months. 
A typical series of values obtained with emulsin, prepared by extracting 
almond paste at about 0°, is contained in Table I. 
Whereas, in the experiments recorded in No. II of these studies, made 
with Merck's relatively inactive emulsin, a series of decreasing values were 
obtained, the values recorded in the upper part of Table I form an increasing 
series. The change follows a straight-line law during at least seven hours 
until about 30 per cent. of the sugar is hydrolysed. Viewed in the light of 
the explanation formerly given, which has found general acceptance,* the 
results are easily explained and significant: obviously only a very small 
quantity of a highly active enzyme was present—so much so, indeed, that the 
magnitude of the active system remained constant during a considerable 
period, until as much as 30 per cent. of the hydrolyte had been attacked. 
Additional proof that this explanation is admissible is given in the lower 
* Compare Bayliss, ‘ Archives des Sciences Biologiques,’ 1904, vol. 11, suppl., p. 261. 
