Issued April 22, 1910. 



UNITED STATES DEPARTMENT OF AGRICULTURE, 



BUREAU OF CHEMISTRY Circular No. 55. 

 H. W. WILEY, Chief of Bureau. 



THE INFLUENCE OF ACIDS AND ALKALIS ON THE ACTIVITY OF 



INVEETASE. 



By C. S. HUDSON and H. S. PAINE, Assistant Chemists. 

 INTRODUCTION. 



The marked influence of the acidity of the medium on the activity 

 of the enzym invertase has been noticed by Kjeldahl, a O'Sullivan and 

 Tompson, & Hudson, and recently by Sorensen ; d the results of these 

 researches may be briefly summarized by the statement that although 

 alkalinity of any strength entirely prevents the action of invertase, 

 slight acidity favors it, but strong acidity prevents it, and there is 

 therefore a concentration of acid for which the enzymotic activity 

 is a maximum. In preliminary experiments it was noticed that the 

 action of acids and alkalis on invertase is twofold, for in some cases 

 the enzym is destroyed but in others it is only temporarily prevented 

 from acting. For example, if a strongly active solution of invertase 

 is made faintly alkaline to litmus and some cane sugar is dissolved 

 in it no inversion of the sugar occurs even after several hours ; if the 

 alkaline solution is then made acid with acetic acid the invertase 

 immediately begins to invert the sugar, showing that the enzym has 

 not been destroyed by the slight alkalinity but only held back or 

 greatly retarded in its normal action. The word inactivation will be 

 used to describe this phenomenon of retardation. On the other hand, 

 if an invertase solution is made strongly alkaline the enzym is per- 

 manently destroyed, as shown by the fact that the addition of acid 

 does not cause any return of enzymotic activity. Invertase is also 

 permanent!} 7 destroyed by strong acidity. The present investigation 

 was made to determine more exactly the conditions of acidity and 

 alkalinity that cause an inactivation of the invertase and those that 

 cause its total destruction. 



a Meddeleiser fra Carlsberg Laboratoriet, 1881, 1 : 337. 

 6 J. Chem. Soc., 1890, 57 : 854. 

 " J. Amer. Chem. Soc., 1908, 30 : 1570. 



d Comptes-rendus des travaux du Laboratoire de Carlsberg. 1909, 8: 1-168. 

 29685 Cir. 5510 



