THE INFLUENCE OF ACIDS AND ALKALIS ON THE ACTIVITY OF 



EMULSIN. 



The enzym emulsin is very sensitive to acids and alkalis. In 

 Table V are recorded a series of measurements of the rate at which 

 a constant quantity of emulsin hydrolyzed at 35 a 4 per cent solu- 

 tion containing different amounts of hydrochloric acid or sodium 

 hydroxid. The results are shown also in figure 2. 



TABLE V. Activity of emulsin toward salicin in add and alkaline solutions. 



a The values of the activity are those of the velocity-coefficient of the hydrolysis (ki), using decimal 

 logarithms and minutes, multiplied by 100,000 to give whole numbers. 

 6 Distilled water. 



Emulsin is entirely inactive toward salicin except in the region 

 just above neutrality. In this respect it resembles the enzym in- 

 vertase, but the range of activity of emulsin does not extend into 

 as strong acidity as does that of invertase, and extends farther into 

 alkalinity. The emulsin solution 

 which was used in the preceding ex- 

 periments was dialyzed several days 

 in order to remove as much as pos- 

 sible of any salts, acids, or alkalis 

 that may have originally been in the 

 infusion of almonds; the dialyzed 

 solutions were neutral to -litmus. 

 Since the curve of activity (fig. 2) o 

 is not very steep at the point of neu- 

 trality, there is no need for making 

 the emulsin solutions slightly acid 

 in order to obtain stead} 7 " and repro- 

 ducible conditions for the hydrolysis, 

 enzym invertase for which the curve is exceedingly steep near the 

 point of neutrality, and the addition of acid to bring the rate into a 

 region where the slope is less steep is quite important. 



[Cir. 47] 



FlO. 2. Influence of acidity and alkalinity on 

 the activity of emulsin. 



This is in strong contrast to the 



