PASTEUR EFFECT 67 



phosphoglyceraldehyde + pyruvate -^ phosphoglycerate -|- lac- 

 tate (58) 



glycogen + phosphate ±5 glucose-1-phosphate (61, 62) 



glucose-1-phosphate ?± glucose-6-phosphate (62) 



adenosinediphosphate + glucose -^ adenyhc acid + glucose-6- 

 phosphate (63) 



The activation by thiol compounds of glycolysis in extracts, de- 

 scribed by Geiger and Magnes (64) and Michaelis and Runnstrom 

 (65) thus becomes easily understandable. 



THIOL INFLUENCE ON FERMENTATION AND GLYCOLYSIS 

 IN INTACT CELLS 



The function of glutathione is not yet well understood. It is 

 present in practically every cell in fairly large amounts. Frequently 

 it has been suggested that it performs the role of an oxidation- 

 reduction buflFer. The very complexity of intracellular metabolism 

 prevents us from making more than vague statements of that type. 

 The protection against oxygen injury which thiol compounds give 

 to strict anaerobes, first observed by Quastel and Stephenson (53), 

 lends support to the assumption that their function is one of 

 stabilization. 



Observations on intact cells as well as on cell-free enzyme systems 

 suggest a regulatory effect of thiol compounds on glycolysis and 

 fermentation. As yet it is impossible to correlate definitely the action 

 on intact fermenting cells and on fermenting enzyme extracts or 

 partial systems, but a promising approach seems to be opened which 

 is worth very careful consideration. 



Release of aerobic glycolysis with glutathione was first observed 

 by Bumm and Appel (66) with sliced animal tissues. Soon after- 

 ward Quastel and Wheatley (40) made an interesting study of the 

 effects of glutathione and cysteine on the metabolism of baker's 

 yeast. One of their experiments is included in Table 7 above. Gluta- 

 thione interrupts the Pasteur effect without affecting respiration. 

 They noted that an extract of brewer's yeast had much the same effect 

 as glutathione, which they ascribe to the large content of thiol com- 

 pounds in brewer's yeast. With cysteine the effect on aerobic glycol- 

 ysis was the same, but respiration was markedly inhibited. The 

 respiratory inhibition was specific for glucose and absent when 

 glycerol was used as substrate. More recently Runnstrom and 

 Sperber (67) undertook a study of the cysteine effect. Accompanying 



