THE CHEMISTRY OF THE SUGARS 



99 



A number of similar compounds have been prepared by 

 Emil Fischer, and it has been found by him and by E. F. 

 Armstrong and others that the a and glucosides show 

 well-defined differences in their resistance to the action of 

 enzymes. It has been further found that if the hexose result- 

 ing from decomposition of the glucoside is added to the 

 reacting mixture of glucoside and enzyme the action is re- 

 tarded. These investigations suggest that the decomposition 

 of glucosides which is effected by enzymes is first preceded 

 by a combination of the glucoside with the specific enzyme. 

 They would indicate that enzymes are also asymmetric 

 products, and in the words of Emil Fischer : ' Enzyme and 

 glucoside must fit each other like key and lock in order that 

 the one may exercise a chemical action on the other.' 



The di-saccharoses have probably a glucosidic structure, 

 saccharose or cane sugar being the glucoside of glucose, with 

 the following probable formula : 



caps: 



The enzymic hydrolysis of the di-saccharoses and poly- 

 saccharoses is of great technical and scientific importance and 

 will be dealt with in separate chapters in the following pages. 



H 2 



