CATALYSIS AND THE ENZYME'S 



Now comes the question what enzymes may 

 be formed of. Very little has hitherto been dis- 

 covered about the origin of enzymes. Only a few 

 hints are given by a series of experimental results. 

 In a number of cases it has been stated that 

 extracts from cells do not contain ready and 

 effective enzymes. But when they are treated 

 with very diluted acetic acid or other milder 

 chemical agents they begin to show distinct 

 working on fat or albuminous matter or on starch. 

 Therefore the supposition was arrived at that the 

 fresh cell-extract contained the natural mother- 

 substance of these enzymes, and that this mother- 

 substance was able to furnish the enzyme itself 

 by artificial transformation. The original sub- 

 stances were called Pro-Enzymes or Zymogens. 



Studies on the pancreatic ferment in animal 

 intestines have shown that the fresh pancreatic 

 juice does not act on protein bodies. But when it 

 is brought together with the intestinal liquid it 

 begins to act most energetically on proteins. The 

 intestinal liquid entirely loses its activating effect 

 when boiled. The activating substance must 

 consequently be destroyed by heat .quite as 

 enzymes are. Other experiments showed that 

 the activating substance of the intestinal sap 

 much resembles a true enzyme, and it may be 

 called an Enzyme activating Enzyme, or Kinase. 



Enzyme effects are assisted also by many other 

 substances. We know the great influence which 

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