Question

Steps 8 and 9 of glycolysis produce no reduced electron carriers or ATP in the conversion of 3-phosphoglycerate into phosphoenolpyruvate. What is the importance of these steps for the ability of glycolysis to produce more energy from glucose?

Answer 1

Answer: Glycolysis is the metabolic pathway in which glucose (a six carbon compound) is converted into pyruvate (2 molecules of three carbon compounds) in cytoplasm of the cells. Result of this pathway ATP and NADH are generated. The conversion of 3-phosphoglycerate into 2-phosphoglycerate with the involvement of enzyme phosphoglycerate mutase that leads to the shift of phosphate group from carbon at position-3 to carbon at position-2 of the compound. The phosphoglycerate mutase reaction has an interesting mechanism: the phosphate group is not simply moved from one carbon to another (C3 to C2). This enzyme requires catalytic amounts of 2,3-bisphosphoglycerate (2,3-PBG) to maintain an active-site histidine residue in a phosphorylated form. The phosphoryl group remain linked to the 2,3-bisphosphoglycerate (2,3-PBG) enzyme, further this phosphate group is transfer to 3-phosphoglycerate to form 2,3-bisphosphoglycerate. So there is no net gen in energy in terms of ATp or the generation of reducing equivalent (NADH) but these steps make the reaction favourable to comple and produce ATP, reducing equivalent as well as the substrate for the further reaction.