CARBOHYDRATES 45 



Fermentation Enzymes 



Under the influence of certain microorganisms the carbohy- 

 drates undergo a process known as fermentation, which consists 

 in the breaking up of the carbohydrate molecule to form a 

 variety of simpler compounds. The nature of the products de- 

 pends upon the character of the particular organism respon- 

 sible for the decomposition. Thus the carbohydrate may form 

 carbon dioxide and alcohol, a process known as alcoholic fer- 

 mentation. Or it may form lactic acid, butyric acid, or still 

 other substances. In alcoholic fermentation we may represent 

 the process as follows: 



C 6 H 12 6 -^2 C 2 H 5 OH+2C0 2 



but in reality there are intermediate steps the character of 

 which is but imperfectly understood. The changes brought 

 about in the sugar in these reactions are due to the fact that the 

 microorganisms involved contain or secrete compounds which 

 have the power of breaking down the sugar. We know a great 

 many of these substances, and their activities are by no means 

 limited to the breaking down of sugars. To them has been given 

 the name of enzymes and different members of this class of sub- 

 stances have the power of bringing about the most widely vary- 

 ing chemical reactions, both breaking down substances and 

 building them up. 



Enzymes have been the object of much study in recent years, 

 but as yet very little is known of their chemical constitution. 

 There is some evidence indicating that perhaps some of the 

 members of the group may be, or may closely resemble proteins, 

 whereas others appear to be carbohydrates. It is altogether 

 probable that they will be found to vary much in their chemical 

 nature, just as they vary in their chemical activities. 



Although little is known of the chemical constitution of the 

 enzymes, many important facts are known concerning their 

 properties and the conditions governing their activities. One 

 of the striking facts of enzyme action is that these substances do 

 not appear combined with the final products which they produce. 



