FRITZ LIPMANN 



miits. Sucli a uiiil is essentially an oxygen hydrogen cell. This unit 

 is further broken down in the scheme of Figure 2, which may be repre- 

 sentative of the respiration not only of carbohydrate but also of other 

 substrates. 



1.2 



-50 



1.0- 



0.8- 



0.6 



04 



0.2 



o 



> 







CYTOCHROMES 



-30 



-FLAVOPROTEINS, 



10 PYRIDINE 

 NUCLEOTIDES 



o 



2H 



~POi- 



PO^ 



•po; 



ADENYLIC 

 ACID 



METABOLITE 

 Figure 2. — ^Transformation of Electron Potential into Phosphate Bond Energy. 



This graph accounts for the energy deficit which appeared in Figure 1 

 as empty space above the substrate flow line. A more detailed picture is ob- 

 tained by fitting into the detours cycles of the type depicted in scheme II, 

 page 146. 



Projection of the potential gradient onto a space scale enables us 

 to fix approximately on the map those regions where transformation of 

 electron potential into phosphate bond energy is to be expected. It 

 is known from a gross comparison between oxygen consumption and the 

 resulting phosphorylation (1,6,15) that, by transport of one pair of hy- 

 drogen electrons from substrate to oxygen, 3+ energy-rich phosphate 

 bonds may be generated. Energy-rich phosphate bonds average 

 12 kcal. per bond, which is equivalent to a span of 0.25 v. for a two- 



144 



