CATALYSIS AND THE ENZYMES 



united in the chemical group of Hydrolytic Enzymes 

 or Hydrolases. Among these enzymes different 

 sub-orders may be distinguished according to the 

 chemical order to which the substance attacked 

 belongs. If esters or compound ethers of alcohols 

 and acids are decomposed by enzymes the latter 

 may be called Esterases ; if they act on carbo- 

 hydrates, Carbohydrases ; if they act on fats, 

 Lipases, etc. 



Other enzymes have the peculiarity that they 

 split off the group NH 2 from nitrogen containing 

 organic substance. Since this group is called the 

 Amido-group, the enzymes must be named 

 Amidases. To such enzymes belong even the 

 most important enzymes which act on proteids, 

 the Proteases. Certain enzymes produce precipita- 

 tions in albuminous solutions by hydrolysis. We 

 call them Coagulases. 



Another group is characterised by the oxidising 

 effects of its enzymes. These are the Oxidases. 

 Their counterpart is formed by the Reductases, or 

 reducing enzymes. Further are known enzymes, 

 which split off carbonic acid from organic acids. 

 We call them Carboxylases. Perhaps even the 

 enzyme which causes the alcoholic fermentation 

 by yeast, the Zymase, belongs to these. 



For physiologists it is rather more interesting to 

 distribute the enzymes according to their physio- 

 logical significance in the living cell. Following 

 the physiological principle, we may distinguish 

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