Inhibition of phosphoenolpyruvate carboxykinase by 6-phosphogluconate in rat liver.

Various concentrations of 6-phosphogluconate inhibit rat liver phosphoenolpyruvate carboxykinase activity. 0.04 mM 6-phosphogluconate, which is the concentration found in vivo, caused a 50% inhibition of 6-phosphoenolpyruvate carboxykinase activity. 6-Phosphogluconate lowered the Vmax of the enzyme and increased the concentration of phosphoenolpyruvate required to achieve one-half of the maximum velocity. The role of 6-phosphogluconate as a regulator of the coordination of fluxes through three metabolic pathways is discussed.