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Phosphofructokinase (PFK) is a glycolytic enzyme that catalyzes the irreversible transfer of a phosphate from ATP to fructose-6-phosphate: fructose-6-phosphate + ATP fructose-1,6-bisphosphate + ADP.In part because of the irreversible nature of this step in glycolysis, PFK is the key regulatory enzyme for glycolysis.When ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur.In this case, PFK's activity is inhibited by allosteric regulation by ATP itself, closing the valve on the flow of carbohydrates through glycolysis.Recall that allosteric regulators bind to a different site on the enzyme than the active (catalytic) site.hen ATP levels are high in the cell, the cell no longer needs metabolic energy production to occur. In this case, PFK's activity is inhibited by allosteric regulation by ATP itself, closing the valve on the flow of carbohydrates through glycolysis.
This step is a direct nucleophilic attack of the hydroxyl group on the terminal phosphoryl group of the ATP molecule (Aleshin, 99). This produces glucose-6-phosphate and ADP. Hexokinase is the enzyme that catalyzes this phosphoryl-group-transfer.exokinase undergoes and induced-fit conformational change when it binds to glucose, which ultimately prevents the hydrolysis of ATP. It is also allosterically inhibited by physiological concentrations of its immediate product, glucose-6-phosphate.