Fructose-1,6-bisphosphate

Definition

Fructose-1,6-bisphosphate is a six-carbon sugar phosphate that plays a crucial role as an intermediate in the glycolytic pathway. It is formed from fructose-6-phosphate through the action of the enzyme phosphofructokinase-1 (PFK-1) and is a key regulatory point in glycolysis, influencing the flow of glucose metabolism and energy production.

5 Must Know Facts For Your Next Test

1. Fructose-1,6-bisphosphate is produced in an ATP-dependent reaction, highlighting its role as a critical control point for energy investment in glycolysis.
2. The concentration of fructose-1,6-bisphosphate can affect the activity of PFK-1, which is considered the main regulatory enzyme of glycolysis.
3. This compound is an allosteric activator of pyruvate kinase, another key enzyme later in glycolysis, facilitating energy production when glucose is abundant.
4. Fructose-1,6-bisphosphate can be converted to intermediates that enter other metabolic pathways, indicating its role not just in glycolysis but also in broader carbohydrate metabolism.
5. It acts as a signal molecule that links glycolytic activity to the energy needs of the cell, demonstrating its importance beyond just being an intermediate.

Review Questions

• How does fructose-1,6-bisphosphate function as a regulatory point in glycolysis?
  • Fructose-1,6-bisphosphate is produced by phosphofructokinase-1, which is a major regulatory step in glycolysis. The level of this compound helps determine the flow through the pathway; if levels are high, it indicates sufficient energy availability and promotes further breakdown of glucose. Conversely, low levels signal reduced energy availability and slow down the process.
• Discuss the interplay between fructose-1,6-bisphosphate and key enzymes in glycolysis.
  • Fructose-1,6-bisphosphate not only serves as an intermediate but also influences other enzymes in glycolysis. It activates pyruvate kinase, enhancing the conversion of phosphoenolpyruvate to pyruvate. Additionally, its production through PFK-1 serves as a commitment step for glucose metabolism, ensuring that when fructose-1,6-bisphosphate is present, energy production continues efficiently.
• Evaluate how the concentration of fructose-1,6-bisphosphate can reflect cellular energy status and influence metabolic pathways.
  • The concentration of fructose-1,6-bisphosphate provides insights into the cellular energy status; high concentrations indicate ample glucose availability and promote glycolytic flux towards energy production. In contrast, lower levels can signal insufficient energy supply. This concentration not only impacts glycolysis but can also redirect metabolites toward gluconeogenesis or other pathways based on the cell's needs for energy or building blocks.

Related terms

Glycolysis: A metabolic pathway that converts glucose into pyruvate, producing ATP and NADH as energy carriers through a series of enzymatic reactions.

Phosphofructokinase-1 (PFK-1): An important enzyme in glycolysis that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, serving as a major regulatory step in the pathway.

Aldolase: An enzyme that catalyzes the cleavage of fructose-1,6-bisphosphate into two three-carbon molecules, glyceraldehyde-3-phosphate and dihydroxyacetone phosphate, during glycolysis.