Issued June 22, 1910. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 59. 

 H. W. WILEY, Chief of Bureau. 



THE DESTRUCTION OF THE ENZYM INVERTASE BY ACIDS, ALKALIS, 



AND HOT WATER. 



By C. S. HUDSON and H. S. 

 Assistant Chemists. 



MEASUREMENTS OF THE BATE OF DESTRUCTION. 



In a previous publication a it was shown that invertase is destroyed 

 by both acids and alkalis. At the temperature of 30 C. the destruc- 

 tive action became noticeable first at the acid concentration of 0.01 

 normal and rapidly increased with the acid strength, becoming almost 

 instantaneous at 0.05 normal; the alkaline destruction began a little 

 below 0.01 normal and became almost instantaneous at 0.045 normal. 

 It is to be supposed that at lower temperatures these rates will all be 

 smaller and that at such temperatures a stronger acidity or alkalinity 

 will be required for a noticeable destructive action. On the other 

 hand, at higher temperatures the rates of destruction will doubtless be 

 greater and the destructive action will be noticeable for weaker concen- 

 trations of acidity and alkalinity. At a sufficiently high temperature 

 the acid and alkaline ions of water itself will doubtless cause a notice- 

 able destructive action of pure water on invertase. It has long been 

 known that hot water destroys invertase and other enzyms; as these 

 views appear to correlate this destruction by hot water with the 

 destruction by acids and alkalis at low temperatures, measurements 

 were made for the purpose of tracing the destructive action of these 

 three agents at different temperatures, in order to learn in what man- 

 ner the actions are related. The measurements were made by the pro- 

 cedure that was described in the former publication; the results being 

 recorded in Table 1 and shown graphically in figure 1. The recorded 

 rates of destruction are the velocity-coefficients of the unimolecular 

 destruction reaction, multiplied by 1,000, the units of measurement 

 being minutes and decimal logarithms. 



U. S. Dept. Agr., Bureau of Chemistry Cir. 55. 

 44161 Cir. 5910 



