The Enzyme Phosphofructokinase Is the Major Regulatory Enzyme of Glycolysis

The enzyme phosphofructokinase is the major regulatory enzyme of glycolysis.It catalyzes

A) the first of the 10 reactions of glycolysis.
B) the isomerization of glucose 6-phosphate to fructose 6-phosphate.
C) the phosphorylation of fructose 6-phosphate.
D) the substrate-level phosphorylation reaction whereby phosphoenolpyruvate is converted to pyruvate.