ANTIBODIES AGAINST RESPIRATORY ENZYMES 369 



All true ester phosphates involving phosphate esterification of alco- 

 holic groups arise exclusively from transphosphorylation with the 

 adenylic system or by intramolecular phosphate split. Inorganic 

 phosphate is never taken directly into alcoholic groups, but only into 

 carbonyl or carboxyl groups. On the other hand, energy-rich phosphate 

 bonds are only created, directly or indirectly, by the oxidative reaction 

 step in phosphorylated intermediates. 



In the preliminary reactions, steps from (3) to (11), glucose is con- 

 verted into a metabolizable form. There is neither oxidation nor re- 

 duction. In these reactions chemical work is done at the expense of 

 the terminal energy-rich phosphate bonds of two molecules of ATP. 

 The free energy changes, with the exception of the phosphorylation of 

 the hexoses and fructose-6-phosphate, is comparatively small. The 

 energy put into the glucose molecule is recovered in two subsequent 

 steps of the reactions of hexose split products. (For an extensive dis- 

 cussion the reader is referred to Lipmann, 1941; Baldwin, 1947.) 



In the oxidation-reduction step involving reactions (14), (15) and 

 (16) nearly as much of the free energy of the oxidation of glyceral- 

 dehyde to the glyceric acid level is taken up by the phosphorylation of 

 ADP to ATP (aF= 10,000 to 12,000 calories/mole of phosphate) as is 

 taken up for the reduction of DPN to DPNH2. The former is a net 

 gain of free energy, while the DPNH2 is reoxidized in the reduction of 

 one mole of pyruvic to lactic acid. The free energy change in this 

 reduction at pH 7 is about +8300 calories. 



The oxidation of phosphoglyceraldehyde to phosphoglyceric acid 

 makes possible the formation of the second energy rich phosphate bond, 

 which is produced by the dehydration of 2-phosphoglyceric acid to 

 phosphopyruvic acid. In this change as much as 8000 calories per mole 

 are liberated. Of this amount, 2000 calories are derived from an in- 

 crease in entropy due to the formation of a C=0 group. 



The high potential energy of (enoO-phosphopyruvate resides in the 

 fact that it is capable of converting ADP to ATP (reaction, 19). This 

 change nets for ATP 1 1,250 calories/mole. 



Thus, as far as the energy rich phosphate bond is concerned, two 

 new molecules of ATP are gained for each molecule of glucose fer- 

 mented. In the yeast fermentation of one mole of glucose, C6Hi206-> 

 2CO2+2CH3CH2OH, the loss of free energy is about 50,000 calories. 

 Two new energy-rich ATP molecules are formed at the cost of one 



