Reaction 3: The Second Investment of ATP•Phosphofructokinase(磷酸果糖激酶,PFK)catalyzes a second ATP-dependentphosphorylation, to give a hexose derivative, fructose-1,6-bisphosphate (FBP), phosphorylated at both carbons 1 and 6.•Transferring the carbonyl oxygen from carbon 1 to carbon 2 has two important effects: •The hydroxyl group generated at carbon 1 can be readily phosphorylated in the reaction 3. •It also sets up the sugar for a symmetric aldol cleavage in reaction 4. •The phosphofructokinase reaction is the primary step at which glycolysis is regulated.