Phosphate Turnover and Pasteur Effect 265 



between mitochondria and cytoplasm. Racker (1956) drew an 

 analogous conclusion from his experiments on ascites tumour 

 cells; so did Chance and Hess (1956) from their spectro- 

 photometric experiments. The results obtained by the latter 

 authors are conclusive proof for the slow phosphorylation of 

 glucose by intramitochondrial ATP. The slow diffusion of 



Respiring 

 cells 



Orthophosphate:- <- 

 (and ADP) 



ATP fo - 



Transitory state 

 following inhibition 

 of oxidative 

 Phosphorylation 



M C 



Fermenting 

 cells 



M 



oooo 

 _oo_ 0. 



oVo _- 



oooo 

 ooOo 

 oO o 



2VJ2 



m 



■r» o 



o ■:. o 



- * -o~o~-|? ~- > o". 



-o -jkro !o_o_- s 



o-o-P- ^1 o - -5 « 



Fig. 6. Schematic representation of the intracellular distribution of in- 

 organic phosphate, ADP and ATP in respiring and fermenting cells. 

 M = mitochondria; C = cytoplasm. Vertical broken line represents 

 barrier between mitochondrial and cytoplasmic compartments. Arrows 

 indicate the directions of transport of inorganic phosphate and ADP ( — ) 

 or of ATP ( O ) in the various states. 



ATP from the mitochondria to hexokinase leads to depletion 

 of ATP at the site of this enzyme. Simultaneously the ATP 

 content of the mitochondrial areas increases. The intracel- 

 lular ADP distribution may be expected to have the comple- 

 mentary pattern. This could explain why sugar phosphory- 

 lation can occur at different rates even if the total amounts 

 of ATP and ADP remain unchanged. The stimulation of 

 sugar uptake by DNP fits well into this picture. After the 

 oxidative phosphorylation has been blocked the level of in- 

 organic phosphate rises and initiates an increased fermenta- 



