Question

IN DETAIL EXPLAIN the Regulation of the glycolysis pathway in eukaryotic cells

Answer 1

The glycolysis control begins with the first enzyme of the pathway i.e hexokinase. Hexokinase catalyzes the phosphorylation of Glucose and the presence of the negatively charged phosphate also prevents the sugar from leaving the cell. If hexokinase is inhibited, glucose comes out of the cell and does not become a substrate for the respiration in that tissue. The product of the reaction catalyzed by hexokinase is glucose-6-phosphate, which accumulates if a later enzyme, phosphofructokinase, is inhibited.

The glycolysis pathway is primarily regulated at the three key enzymatic steps. These enzymeatic conversions are catalyzed by 3 enzymes which are hexokinase, phosphofructo kinase and and pyruvate kinase. The first 2 enzymes also result in ATP hydrolysis and regulate the first and 3rd steps of glycolysis. High levels of ATP or citrate or a lower, more acidic pH decreases the activity of phosphofructo kinase.

The last step in glycolysis is catalyzed by pyruvate kinase. The pyruvate produced can be catabolized or converted into alanine. If no more energy is needed and alanine is in adequate supply, the enzyme is inhibited. Its activity is increased when fructose-1,6-bisphosphate levels increase. The regulation of pyruvate kinase involves phosphorylation by pyruvate kinase. It slows down it's activity but it's dephosphorylation by phosphatase activates it again.