fructosa16bisphosphatasa

Fructose-1,6-bisphosphatase, abbreviated FBPase and also known as fructosa-1,6-bisfosfatasa in some languages, is a metalloenzyme that hydrolyzes fructose-1,6-bisphosphate to fructose-6-phosphate and inorganic phosphate. It is a central enzyme in gluconeogenesis, the metabolic pathway that generates glucose from non-carbohydrate precursors, and it also functions in the Calvin cycle of photosynthetic organisms to regenerate the carbohydrate acceptor.

The enzyme requires divalent metal ions such as Mg2+ or Mn2+ for catalysis. In many organisms, activity is regulated allosterically: AMP inhibits FBPase-1, while fructose-2,6-bisphosphate acts as a potent inhibitor in organisms that possess the bifunctional PFK-2/FBPase-2 enzyme, linking glycolysis and gluconeogenesis to cellular energy status. In plants, chloroplast FBPase is subject to redox regulation by thioredoxin, activating the enzyme in light conditions.

FBPase exists in multiple subcellular locations; cytosolic FBPase supports gluconeogenesis in animals and many microbes, while plastidial or chloroplast forms operate in photosynthetic tissues. Structural studies show a conserved fold with a catalytic metal center; most forms function as oligomeric assemblies, and the enzyme is commonly encoded by FBP1-family genes.

Clinical and physiological relevance: FBPase is essential for glucose production during fasting; defects or altered regulation can contribute to metabolic imbalances. In plants and some bacteria, dual localization and co-regulation with other metabolic steps reflect integration into broader carbohydrate metabolism.