144 ORGANIC AGRICULTURAL CHEMISTRY 



trypsinogen. In this case the activator or kinase is another 

 enzyme present in the intestinal juice known as enterokinase. 

 When these two substances, the trypsinogen and enterokinase, 

 come together, the active enzyme trypsin is the result. The 

 activator may thus be another enzyme or a non-enzyme sub- 

 stance like hydrochloric acid. 



Co-enzymes and Anti-enzymes. — It has also been shown 

 that an enzyme may not be a single unit, but may consist of two 

 parts known as the enzyme and the co-enzyme. The activity of 

 the enzyme is dependent upon the presence of its complement 

 the co-enzyme. These two substances have been separated 

 in the case of the enzyme zymase and activity results only when 

 the two are present together. The nature of the co-enzyme is 

 not well established. 



Also there have been shown to be substances present in the 

 animal body which prevent the action of certain enzymes. 

 These have been called anti-enzymes. These anti-enzymes are 

 exceedingly important and are connected with the action of 

 toxins and the condition known as immunity. 



Without going into detail we have thus presented the main 

 known facts and theories in regard to enzymes and enzymatic 

 action. What has been said will help us to understand what 

 will be presented later on in connection with the digestion, 

 absorption and metabolism of food both in plants and in ani- 

 mals. In all of the chemical reactions connected with the phys- 

 iological processes of living organisms enzymes are, no doubt, 

 the catalytic agent. In both plants and animals they are 

 abundant, probably much more so than our present knowledge 

 establishes. It may emphasize their importance in animal 

 physiology to state that in the liver alone there are probably 

 fifteen or more distinct enzymes that have been shown to be 

 active. 



Names of Enzymes 



The name of an enzyme, where a systematic name has been 

 applied, is made up from the name of the substance upon which 

 the enzyme acts and the termination ase. The enzymes re- 



