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Glycolysis is the conversion of one molecule of glucose into two pyruvate molecules, two hydrogen ions, and two molecules of water. The high-energy molecules ATP and NADHare generated in this process.

The three enzymes that are potential control points are:

• Hexokinase is an enzyme found in all cells that catalyzes the conversion of glucose into glucose-6-phosphate when it enters the cell. Because this is the initial step in the glycolytic pathway in the liver, it adds another layer of regulation.
• Phosphofructokinase is a crucial regulatory point because it is one of the irreversible enzymes in the glycolytic process and possesses significant allosteric effectors, AMP and fructose 2,6-bisphosphate. Fructose 2,6-bisphosphate is a powerful activator of phosphofructokinase, which is produced when fructose-6-phosphate is phosphorylated by another phosphofructokinase.
• Pyruvate kinase catalyzes the last stage of glycolysis, resulting in pyruvate and ATP formation. Pyruvate kinase catalyzes the transfer of a phosphate group from phosphoenolpyruvate to ADP, yielding one pyruvate molecule and one ATP molecule.

Enzymes that catalyze fundamentally irreversible reactions are possible locations of control in metabolic pathways. Hexokinase, phosphokinase, and pyruvate kinase are the three regulating enzymes in glycolysis.