CATALYSIS AND THE ENZYMES 



less activity than the original enzyme. We must 

 confess that it is at present impossible to say 

 Whether all enzymes belong to ihe class of al- 

 buminous substances, as in many cases seems 

 probable, or whether enzymes may be of different 

 chemical structure. It is not even certain whether 

 all enzymes contain nitrogen. 



As far as we know all enzymes are distinctly 

 colloidal substances. No enzyme survives boiling 

 even for a short time. Although there is great 

 uncertainty about the chemical nature and 

 relation of enzymes we possess much knowledge 

 of the action of enzymes, which is doubtless the 

 most interesting part of their characteristics. 

 At the first glance we must feel reminded of 

 catalytic reactions. Berzelius made no difference 

 between enzymes and catalytic substances. As 

 well as being catalysers the enzymes show strong 

 actions even when applied in but very small 

 quantities. It was stated with regard to a series 

 of enzyme reactions that the quantity of the 

 enzyme is not diminished in a perceptible degree 

 during the reaction. We know further that the 

 enzyme never appears among the products of a 

 reaction, quite as in catalytic reactions. Finally, 

 it is most probable that the reactions which are 

 caused by enzymes do not entirely depend for their 

 existence upon the presence of the enzyme. They 

 are continued and take place, though very slowly, 

 even when the enzyme is not present. We see that 

 H 97 



