196 CHEMISTRY OF PLANT LIFE 



cose by maltase; the production of ethyl butyrate from alcohol 

 and butyric acid; and the synthetic production of artificial fats, by 

 the aid of the pancreatic lipase; and the apparent synthesis of a 

 protein from the same amino-acids which may be obtained from it 

 by hydrolysis under the influence of the same protease, but under 

 different environmental conditions. 



^ ACTIVATORS AND INHIBITORS 



The activity of enzymes is strongly influenced by the presence 

 in the solution of other bodies, usually, although not always, elec- 

 trolytes. This is probably due, in most cases at least, to the action 

 of the electrolyte upon the colloidal condition of the enzyme. All 

 enzymes do not respond alike to the action of the same electrolyte, 

 however. The activity of certain enzymes is enormously increased 

 by the presence of a small amount of acid; while the action of 

 another may be absolutely inhibited by the same acid in the same 

 concentration. Thus, the activity of the amylase found in the 

 endosperm of many seeds is instantly stopped by adding to the 

 solution enough sulfuric acid to make it two-hundredth normal in 

 strength; while the same concentration of acid actually accel- 

 erates the activity of some of the proteases. 



Formaldehyde, hydrocyanic acid, and soluble fluorides usually 

 inhibit both the activity of a cell and of the enzymes which it 

 contains; while other antiseptics, such as toluene, xylene, etc., 

 prevent the growth of the cell, or organism, without interfering 

 with the activity of the enzymes which may be present. By the 

 use of this latter type of antiseptics, it is possible to distinguish 

 between chemical changes which are involved in the actual devel- 

 opment of a cell and those which can be brought about in other 

 media by means of the enzymes which are contained in the 

 cell. 



Any substance which increases the catalytic activity of an 

 enzyme is known as an " accelerator," or " activator"; while one 

 which prevents this activity is called an " inhibitor," or " para- 

 lyzer." 



A type of accelerating influence quite different from that of 

 electrolytes is found in the effect of certain amino-acids upon 

 enzyme action. The influence of small amounts of asparagine in 

 enormously increasing the hydrolytic effect of amylase is an exam- 



