ENERGY SUPPLY OF THE CELL 75 



for intramolecular oxido-reductions of type 2 (p. 70) 

 where acceptor and donator are the same molecule, 

 the above data cannot be applied. 



In intramolecular fermentations, energy is liberated 

 by shifting the oxygen towards the end-carbon, and by 

 massing the oxygen on one carbon rather than having it 

 distributed evenly to the various carbon atoms. As 

 an example, we can write the glucose molecule and its 

 products thus: 



H H H H H H 



HC . C . C . C . C . C glucose 







H H H H H 



O H H H H O 



C HC . CH HC . CH C alcohol + CO2 



O O H H O O 



H H 



O H H H H O 



C . C . CH HC . C . C lactic acid 



O O H H O O 



H H H H 



The shifting of oxygen from the inner to the outer carbon 

 atoms liberates energy. A compound with oxygen on 

 the outer carbons only can not undergo an intramolecular 

 oxido-reduction. All the simple alcohols, all fatty acids 

 (and, of course, all hydro-carbons), as well as the divalent 

 acids like oxalic, malonic and succinic acid can not be 

 fermented except by a different type of hydrogen 

 acceptor, such as oxygen gas or nitrate or perhaps certain 

 protein products. Organic acids may undergo decar- 

 boxylation, but that does not, as a rule, lead to a gain 



