THE PROTECTIVE ACTION OF FRUCTOSE AGAINST THE 

 DESTRUCTION OF IN VERT A SE. 



Recently the authors have shown the very marked effect of cane 

 sugar in protecting 1 invertase from destruction by alcohol; experi- 

 ments will now be described which show that fructose shares with 

 cane sugar this remarkable property, and also protects invertase from 

 destruction by acids and alkalis. The latter protective action has not 

 yet been tested for cane sugar. The experiments were made by the 

 usual procedure, the rate of destruction being measured first in the 

 absence of fructose and then with it present in the concentrations of 

 2.7, 5.4, and 10.9 per cent. The data are recorded in Table 3 and 

 the action of fructose in protecting invertase from acid destruction 

 is shown in figure 2. 



TABLE 3. The action of fructose in protecting invertase from destruction by acids, alkalis, 



and hot water. 



The rates of destruction given in the table are expressed as per 

 cent of the rate for the destroyer when no fructose is present. The 

 rates actually found, expressed as velocity-coefficients of the uni- 

 molecular destruction reaction, using minutes and decimal logarithms, 

 are 0.04 normal hydrochloric acid, 0.096; 0.03 normal sodium hydroxid, 

 0.050; 50 per cent alcohol, 0.85; and water, 0.0052. 



It will be seen from the figure that the protective action of fructose 

 in the case of hydrochloric acid is not at all proportional to the con- 

 centration of the sugar but approaches a limiting value asymptotically. 

 The limiting value for the protection seems to have been reached in 

 the case of the alkaline solutions and the alcohol with only 2.7 per 

 cent fructose; this is probably also true for the protection from hot 



U. S. Dept. Agr., Bureau of Chemistry Cir. 58. 



[Cir. 59] 



