fruktoosi6phosphate

Fruktoosi6phosphate, more commonly known as fructose-6-phosphate (F6P), is a phosphorylated hexose sugar that functions as a central intermediate in carbohydrate metabolism. It is formed from glucose-6-phosphate by the enzyme phosphoglucose isomerase and serves as a key junction point between glycolysis and other metabolic pathways.

In glycolysis, fructose-6-phosphate is a substrate for phosphofructokinase-1 (PFK-1), which phosphorylates it to fructose-1,6-bisphosphate. This reaction commits glucose metabolism to the downstream steps of glycolysis and helps regulate the rate of ATP production. The activity of PFK-1, and thus the flow from F6P into glycolysis, is influenced by cellular energy status and hormonal signals, making F6P a node of metabolic control.

Fructose-6-phosphate can also enter the pentose phosphate pathway through the non-oxidative branch, where it is interconverted with glyceraldehyde-3-phosphate, ribose-5-phosphate, and other triose or pentose phosphates. This interconversion links glycolytic flux with nucleotide and reductive biosynthesis, and it enables the cell to balance demands for reducing power (NADPH) and ribose sugars.

Chemically, fructose-6-phosphate is a hexose phosphate with a phosphate group attached to the sixth carbon. In solution, it exists in equilibrium between open-chain and cyclic forms. It is a widely conserved metabolite found in many organisms and tissues as part of basic carbohydrate metabolism.