fruktozo16bisfosforanu

Fruktozo16bisfosforanu, known in English as fructose-1,6-bisphosphate (FBP), is an intermediate in carbohydrate metabolism, specifically in glycolysis and gluconeogenesis. It is formed from fructose-6-phosphate by the enzyme phosphofructokinase-1 (PFK-1) using one molecule of ATP. This phosphorylation step is a key regulatory point and often the rate-limiting step of glycolysis.

FBP is then cleaved by aldolase into two triose phosphates: dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (G3P). DHAP can be converted to G3P by triose phosphate isomerase, allowing all carbon atoms to continue through glycolysis.

In metabolism, fructose-1,6-bisphosphate can act as a feed-forward activator of pyruvate kinase, helping to accelerate glycolytic flux in response to cellular energy demand. In gluconeogenesis, FBP is dephosphorylated by fructose-1,6-bisphosphatase to fructose-6-phosphate, a major control step that opposes the action of PFK-1.

Chemical and physical properties: FBP is a charged, water-soluble sugar phosphate with two phosphate groups attached to the 1 and 6 positions of fructose. At physiological pH, it exists primarily in phosphorylated, dianionic forms.

Biological significance: As a central glycolytic intermediate, FBP links carbohydrate metabolism to energy production and participates in broader metabolic regulation across many organisms. Its levels reflect and influence cellular energy status and flux through glycolysis and gluconeogenesis.