ENZYMES 



173 



free to move around in the space occupied by the macromolecule. Accord- 

 ing to this conception, the electrons are poured into a "pool" covering the 

 macromolecule and the tributaries of this pool are the hydrogen bonds 

 between the polypeptide chains. In this context, an enzyme is a semi- 

 conductor of greater efficiency than an ordinary non-enzymatic protein. 



In the explanation of the hydrolytic action outlined above, the enzyme 

 is considered as a conductor of electrons through which an electron flow 

 takes place, so modifying the distribution of electrons that certain bonds 

 are ruptured. 



For the hydrolysis of a peptide, the picture will be as follows : 



O H 



o- 



H 



R— C— N— R' 



H— O 



I 

 H H 



o- 



I 

 0=C N+ 



Enzyme 



R— C- 



I 

 HO+ 



I 

 H- 



I 

 O 



o=c 



-N— R' 



H 



N- 



Enzyme 



i 



O 



R— C 4- R'NHz 



OH 



H 



I 

 O 



I 

 0=C N 



Enzyme 



B. Coenzymes 



When the enzyme requires a coenzyme, we know a little more about the 

 mechanism, at least as far as the latter is concerned. 



If, for example, we consider the lactic dehydrogenase system, we may 



