Pasteur effect, oxygen inhibition

Pasteur Effect The inhibition of glycolysis by oxygen discovered by Pasteur when he found that aerobic yeast cultures metabolize glucose relatively slowly. 

The early work of Meyerhof showed that there was an intimate connection between resynthesis of carbohydrate and aerobic metabolism. When the production of lactic acid by tissues under anaerobic conditions was compared with the production of lactic acid under aerobic conditions, it was found that the uptake of 1 mole of respired oxygen inhibited the formation of 1 to 2 moles of lactic acid i.e., three to six times as much lactic acid as could have been oxidized by the observed oxygen uptake. This phenomenon of the suppression of glycolysis under aerobiosis has been called by Warburg the Pasteur effect. 

The Pasteur Effect.—Fermentation is characterised by a high rate of carbohydrate destruction and an accumulation of incompletely oxidised end-products. It is antagonised by free oxygen, which preserves the carbohydrates of the cell from extravagant w astage, and restricts the products of anaerobic metabolism. This inhibition of fermentation by oxygen is termed, the Pasteur effect. 

The Pasteur Effect. It is an old observation that cells, e.g. of muscle or yeast, transform much glucose (to lactate or ethanol) imder anaerobic conditions. If oxygen is supplied, however, then not only is anaerobic glycolysis inhibited, but much less glucose actually enters the Embden-Meyerhof pathway. Evidently, the oxidative processes of mitochondria exert some influence back on the cytoplasm. This seems rather sensible physiologically, since in aerobiosis a great quantity of ATP is produced in the respiratory chain and the demands for energy can w ell be met with less substrate. However, this does not explain the mechanism responsible for the effect, which is known as the Pasteur effect. ... 

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