Phosphoglycerate kinase

Definition

Phosphoglycerate kinase is an enzyme that catalyzes a key step in glycolysis, specifically the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate while transferring a phosphate group to ADP to form ATP. This enzyme plays a crucial role in the energy-yielding phase of glycolysis, contributing to the production of ATP that cells use for energy. Its activity is essential for the efficient metabolism of glucose and the overall energy balance within the cell.

5 Must Know Facts For Your Next Test

1. Phosphoglycerate kinase operates at the seventh step of glycolysis, where it catalyzes a reaction that produces one molecule of ATP for every molecule of glucose processed.
2. The enzyme is regulated by the availability of substrates and products, ensuring that ATP production is matched to cellular energy needs.
3. It requires magnesium ions (Mg²⁺) as a cofactor for its enzymatic activity, playing a critical role in stabilizing the transition state during the reaction.
4. Phosphoglycerate kinase is found in both aerobic and anaerobic organisms, emphasizing its importance across different metabolic pathways.
5. Mutations or deficiencies in phosphoglycerate kinase can lead to glycolytic enzyme disorders, which can have significant impacts on cellular metabolism and energy production.

Review Questions

• How does phosphoglycerate kinase contribute to ATP production during glycolysis?
  • Phosphoglycerate kinase contributes to ATP production by catalyzing the transfer of a phosphate group from 1,3-bisphosphoglycerate to ADP, resulting in the formation of ATP. This reaction occurs during the energy-yielding phase of glycolysis and is an example of substrate-level phosphorylation. By converting high-energy intermediates into ATP, phosphoglycerate kinase plays a pivotal role in ensuring that cells meet their energy demands during glucose metabolism.
• Discuss the regulatory mechanisms involved in the activity of phosphoglycerate kinase during glycolysis.
  • Phosphoglycerate kinase is regulated primarily by the concentrations of its substrates, 1,3-bisphosphoglycerate and ADP, as well as the product 3-phosphoglycerate. An increase in 1,3-bisphosphoglycerate or ADP enhances its activity, promoting ATP synthesis when energy levels are low. Conversely, high levels of ATP or 3-phosphoglycerate can inhibit its activity, reflecting the cell's energy state and preventing excess ATP production when not needed.
• Evaluate the impact of phosphoglycerate kinase deficiencies on cellular metabolism and overall health.
  • Deficiencies in phosphoglycerate kinase can lead to impaired glycolytic function and result in reduced ATP production, significantly affecting cellular metabolism. This condition may cause symptoms such as muscle weakness and fatigue due to insufficient energy supply for muscle contraction and other cellular processes. In severe cases, it can lead to hemolytic anemia as red blood cells rely heavily on glycolysis for energy. Understanding these impacts highlights the importance of this enzyme not just in metabolism but also in overall health.

Related terms

glycolysis: A metabolic pathway that breaks down glucose into pyruvate, generating ATP and NADH in the process.

substrate-level phosphorylation: The direct production of ATP from ADP through the transfer of a phosphate group from a high-energy substrate, as occurs in the action of phosphoglycerate kinase.

1,3-bisphosphoglycerate: A high-energy intermediate in glycolysis that is converted to 3-phosphoglycerate by phosphoglycerate kinase, facilitating ATP production.