Figure 36.6: Regulation of glycolysis: (A) Covalent Modification (B) Alloteric regulation of enzymes of glycolysis.

3. Allosteric regulation- All the three crucial enzymes Hexokinase, phosphofructokinase and pyruvate kinase of glycolysis are regulated allosterically (Figure 36.6, B). In  an allosteric regulation, an enzyme binds the allosteric molecules and this modulates the activity of the enzyme either in positive or negative manner.In glycolysis, fructose 2,6 bis phosphate is produced from fructose-6, phosphate by the enzyme phosphofructo kinase-2. fructose 2,6 bis phosphate is allosterically activating the enzymatic activity of phospho fructokinase (PFK-1) and the same time it is down regulating the activity of fructose 1,6 bis phosphatase. In addition, ATP and citrate is inhibiting the activity of phospho fructokinase where as ADP and AMP is allosterically enhancing the enzymatic activitiy.