8 



SUMMARY. 



The conclusions of our investigation, which had for its purpose the 

 development of an accurate polariscopic method for measuring the 

 activity of the enzym emulsin, may be summarized as follows: The 

 glucose which is produced from salicin by the action of emulsin is 

 shown to have the rotation 15 to 25, agreeing with the known 

 rotation of /3-glucose, 20, and differing entirely from that of a-glucose, 

 110. The glucose from salicin is therefore ^-glucose. A secondary 

 reaction, the mutarotation of glucose, affects the polariscopic readings 

 of the salicin solutions during the hydrolysis by emulsin and is the 

 chief source of error in the measurements of Henri, who found that 

 the hydrolysis does not follow the unimolecular order. No such 

 error is present in the measurements of the hydrolysis of salicin by 

 acids, studied by A. A. Noyes and Hall, because the strong acid and 

 the high temperature (95 ) which were employed made the rate 

 of mutarotation instantaneous in comparison with the rate of the 

 hydrolysis; they found that the rate of the acid hydrolysis follows 

 the unimolecular order. The authors have measured the real rate 

 of the hydrolysis of salicin by emulsin at and 30 by making the 

 solution slightly alkaline before reading it in the polariscope, and this 

 rate was found to follow the unimolecular order. Emulsin is active 

 in only a small region of acidity and alkalinity near the neutral point, 

 as shown in figure 2. It is intended to apply this accurate polari- 

 scopic method to a further study of the hydrolysis of salicin and other 

 substances by emulsin, in order to learn the laws of the action of 

 this enzym. 



[Cir. 47] 



