﻿1903] EXPERIMENTAL STUDIES ON INULASE 31 



experiment was tried. Four test tubes were filled as follows, the 

 inulin solution used containing Aspergillus powder in suspension : 



No. I. 10*=^ inulin solution + 10" of 0.02 N. HsSO^^ 



No. 2. 10^*^ inulin solution + 10" of o.i N. H2SO4 



No. 3. 10^^ inulin solution -|- 10^^ of 0.02 N. KOH 



No. 4. lo*'^ inulin solution -j- 10" of o.i N. KOH 



Each tube was corked and placed in the incubator for twenty- 

 four hours, at the expiration of which the solutions were neutral- 

 ized ; each solution was divided into two parts, one of which was 

 boiled. The resulting eight solutions were kept in the incubator 

 for ten days and then examined for levulose. In no case was 

 more sugar present in the unboiled than in the boiled solution. 

 We may conclude, therefore, that the enzyme had been destroyed 

 in each test. 



From an examination of the results of the experiments 

 detailed above, it is evident that the optimum reaction for the 

 inulase of Aspergillus 7iiger and of Penicillium glaucum is very 

 close to 0.000 1 normal acid (sulphuric). This corresponds well 

 with Green's statement concerning the inulase from Helianthus, 

 which, he says, '* works most advantageously in a neutral or very 

 faintly acid medium, the best proportion of acid being about 

 0.001 per cent, of hydrochloric acid.'* Green also says that 

 ''alkalies are deleterious," a fact which agrees with the results 

 of the experiments on inulase from Aspergillus and Penicillium. 

 The reaction of the fluid seems to have the same effect on the 

 enzyme obtained from each of the two fungi. 



INFLUENCE OF THE TEMPERATURE ON THE ACTIVITY OF INULASE. 



In his recent book on the enzymes Effront^ states that "the 

 optimum temperature of inulase is found between 50 and 60°." 

 He gives no authority for the statement, neither does he bring 

 forward any experimental evidence. Bourquelot says that inulase 

 survives a temperature of 64°, but makes no statement in regard 

 to its optimum working temperature. Green states that inulase 

 acts better at 40° than at room temperature, but loses its activity 

 at between 70 and 80°. The unusually high temperature given 



'Enzymes and their application. Translated by Samuel C. Prescott. pp. 249- 

 251. Ne%vYork. 1902. 



