Direct evidence that pyrophosphate: Fructose‐6‐phosphate phosphotransferase can act as a glycolytic enzyme in plants

Experiments were carried out to provide direct evidence that pyrophosphate: fructose‐6‐phosphate phosphotransferase (PFP) can operate as a glycolytic enzyme in some circumstances. A large increase in the rate of glycolysis was produced by adding uncoupler and alkalinising the medium of heterotrophic Chenopodium rubrum cells. Initially, a marked decrease in phospho enol pyruvate, 3‐phosphoglycerate and hexose phosphates occurred, but no change in fructose 2,6‐bisphosphate or inorganic pyrophosphate was observed. However, a gradual increase in the rate of O 2 uptake during the subsequent 5 min was accompanied by an increase in fructose 2,6‐bisphosphate and a decrease in pyrophosphate, providing evidence that activation of PFP contributes to the increase in rate of glycolysis. This was accompanied by partial recovery of the adenine nucleotide energy status.