Phosphoglycerate kinase

Definition

Phosphoglycerate kinase is an enzyme that catalyzes the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate in the glycolytic pathway, along with the concurrent transfer of a phosphate group to ADP, forming ATP. This step is crucial for energy production during glycolysis, as it represents one of the substrate-level phosphorylation reactions that directly generates ATP. Additionally, this enzyme plays a significant role in regulating the flow of metabolites through glycolysis and connecting carbohydrate metabolism to energy yield.

5 Must Know Facts For Your Next Test

1. Phosphoglycerate kinase catalyzes one of the only two substrate-level phosphorylation steps in glycolysis, generating ATP from ADP.
2. The reaction involves a high-energy intermediate, 1,3-bisphosphoglycerate, which donates a phosphate group during the conversion.
3. This enzyme requires magnesium ions (Mg2+) as a cofactor to assist in the proper positioning and stabilization of substrates.
4. Phosphoglycerate kinase activity can be influenced by allosteric effectors, such as ATP and AMP, which help regulate energy metabolism.
5. Deficiencies in phosphoglycerate kinase can lead to metabolic disorders, including exercise intolerance and hemolytic anemia.

Review Questions

• How does phosphoglycerate kinase contribute to the overall energy yield during glycolysis?
  • Phosphoglycerate kinase plays a critical role in glycolysis by facilitating substrate-level phosphorylation, which directly generates ATP from ADP. This reaction converts 1,3-bisphosphoglycerate into 3-phosphoglycerate while transferring a phosphate group. By producing ATP at this stage, phosphoglycerate kinase significantly contributes to the energy yield of glycolysis, ensuring that cells have sufficient energy for metabolic processes.
• Discuss how the activity of phosphoglycerate kinase can be regulated and its implications for cellular energy metabolism.
  • The activity of phosphoglycerate kinase can be regulated through allosteric mechanisms involving ATP and AMP levels within the cell. When energy levels are high (indicated by increased ATP), the enzyme's activity may be inhibited to prevent excessive ATP production. Conversely, low ATP levels or high AMP levels stimulate the enzyme's activity, promoting glycolysis and enhancing energy production. This regulation ensures that cellular energy metabolism is finely tuned to meet the demands of the cell.
• Evaluate the consequences of phosphoglycerate kinase deficiency on human health and how it impacts metabolic pathways.
  • Deficiency in phosphoglycerate kinase can lead to serious health issues such as exercise intolerance and hemolytic anemia. The lack of this enzyme disrupts normal glycolytic function, leading to reduced ATP production and impaired energy metabolism. As a result, muscle tissues may suffer from insufficient energy during physical activity, while red blood cells can become compromised due to their reliance on glycolysis for ATP generation. This deficiency highlights the importance of phosphoglycerate kinase in maintaining metabolic homeostasis and overall health.

Related terms

Glycolysis: A metabolic pathway that converts glucose into pyruvate, producing ATP and NADH in the process.

ATP: A high-energy molecule that serves as the primary energy currency in cells, essential for various biological processes.

Substrate-level phosphorylation: A method of generating ATP by transferring a phosphate group directly from a phosphorylated substrate to ADP, as seen in specific steps of glycolysis.