MICROBIAL METABOLISM AND ITS INDUSTRIAL IMPLICATIONS 



common in living cells are characterized by the fact that the splitting 

 off of the phosphate group is accompanied by an unusually strong 

 decrease in free energy. This implies that the phosphorylated com- 

 pound has a much higher energy content than the phosphate-free 

 moiety, and that therefore this moiety may, simultaneously with the 

 dephosphorylation, enter into reactions which otherwise would be im- 

 possible (Table XI). Amongst cell constituents with such energy-rich 

 phosphate bonds I mention here adenosine triphosphate - as far as the 

 pyrophosphate bonds are concerned - the acetyl phosphate discov- 

 ered by Lipmann, and two compounds we have met in the scheme of 

 the sugar dissimilation, namely 1,3-diphosphoglyceric acid and phos- 

 pho-enol pyruvic acid. We have seen that the intermediate formation 

 of these latter compounds in sugar fermentation leads to the formation 

 of ATP out of ADP, ultimately implying that the integrate formulation 

 of the process of alcoholic fermentation is given by the equation re- 

 produced in Table XII. 



TABLE XII 



Integrate formulation of the processes of: 



(a) Alcoholic fermentation: 



G 6 H 12 6 +2ADP+ 2 H 3 P0 4 -> 2C 2 H 5 OH+ 2 C0 2 +2ATP+2H 2 



(b) Respiration: 



G 6 H 12 O ti +60 2 +32ADP+32H 3 P0 4 -> 6C0 2 +32ATP+38H 2 



ADP = adenosine diphosphate 

 ATP = adenosine triphosphate 



By analogy there is reason to accept the integrate formulation of the 

 respiration process as given in the same table, although this formula- 

 tion bears, as we have already remarked, an almost fully empirical 

 character, the reactions leading to this abundant ATP formation 

 having been only partly revealed. 



In any case there is nowadays no doubt that ATP should be con- 

 sidered as the material link between the energy-yielding dissimilatory 

 processes and the energy-demanding assimilatory processes. Through 

 its two energy-rich phosphate bonds ATP gives rise to the formation 

 of other compounds with similar bonds, which compounds then act 



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