The enzyme fructose bisphosphatase (EC 3.1.3.11; systematic name D-fructose-1,6-bisphosphate 1-phosphohydrolase) catalyses the conversion of fructose-1,6-bisphosphate to fructose 6-phosphate in gluconeogenesis and the Calvin cycle, which are both anabolic pathways:
Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes of glycolysis. It is an allosteric enzyme made of 4 subunits and controlled by many activators and inhibitors. PFK-1 catalyzes the important "committed" step of glycolysis, the conversion of fructose 6-phosphate and ATP to fructose 1,6-bisphosphate and ADP. Glycolysis is the foundation for respiration, both anaerobic and aerobic. Because phosphofructokinase (PFK) catalyzes the ATP-dependent phosphorylation to convert fructose-6-phosphate into fructose 1,6-bisphosphate and ADP, it is one of the key regulatory steps of glycolysis. PFK is able to regulate glycolysis through allosteric inhibition, and in this way, the cell can increase or decrease the rate of glycolysis in response to the cell's energy requirements. For example, a high ratio of ATP to ADP will inhibit PFK and glycolysis. The key difference between the regulation of PFK in eukaryotes and prokaryotes is that in eukaryotes PFK is activated by fructose 2,6-bisphosphate. The purpose of fructose 2,6-bisphosphate is to supersede ATP inhibition, thus allowing eukaryotes to have greater sensitivity to regulation by hormones like glucagon and insulin.
Diphosphate—fructose-6-phosphate 1-phosphotransferase also known as PFP is an enzyme of carbohydrate metabolism in plants and some bacteria. The enzyme catalyses the reversible interconversion of fructose 6-phosphate and fructose 1,6-bisphosphate using inorganic pyrophosphate as the phosphoryl donor:
The Calvin cycle,light-independent reactions, bio synthetic phase,dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis is a series of chemical reactions that convert carbon dioxide and hydrogen-carrier compounds into glucose. The Calvin cycle is present in all photosynthetic eukaryotes and also many photosynthetic bacteria. In plants, these reactions occur in the stroma, the fluid-filled region of a chloroplast outside the thylakoid membranes. These reactions take the products of light-dependent reactions and perform further chemical processes on them. The Calvin cycle uses the chemical energy of ATP and reducing power of NADPH from the light dependent reactions to produce sugars for the plant to use. These substrates are used in a series of reduction-oxidation reactions to produce sugars in a step-wise process; there is no direct reaction that converts several molecules of CO2 to a sugar. There are three phases to the light-independent reactions, collectively called the Calvin cycle: carboxylation, reduction reactions, and ribulose 1,5-bisphosphate (RuBP) regeneration.
Phosphofructokinase-2 (6-phosphofructo-2-kinase, PFK-2) or fructose bisphosphatase-2 (FBPase-2), is an enzyme indirectly responsible for regulating the rates of glycolysis and gluconeogenesis in cells. It catalyzes formation and degradation of a significant allosteric regulator, fructose-2,6-bisphosphate (Fru-2,6-P2) from substrate fructose-6-phosphate. Fru-2,6-P2 contributes to the rate-determining step of glycolysis as it activates enzyme phosphofructokinase 1 in the glycolysis pathway, and inhibits fructose-1,6-bisphosphatase 1 in gluconeogenesis. Since Fru-2,6-P2 differentially regulates glycolysis and gluconeogenesis, it can act as a key signal to switch between the opposing pathways. Because PFK-2 produces Fru-2,6-P2 in response to hormonal signaling, metabolism can be more sensitively and efficiently controlled to align with the organism's glycolytic needs. This enzyme participates in fructose and mannose metabolism. The enzyme is important in the regulation of hepatic carbohydrate metabolism and is found in greatest quantities in the liver, kidney and heart. In mammals, several genes often encode different isoforms, each of which differs in its tissue distribution and enzymatic activity. The family described here bears a resemblance to the ATP-driven phospho-fructokinases, however, they share little sequence similarity, although a few residues seem key to their interaction with fructose 6-phosphate.
Fructosephosphates are sugar phosphates based upon fructose, and are common in the biochemistry of cells.
Fructose 1,6-bisphosphate, also known as Harden-Young ester, is fructose sugar phosphorylated on carbons 1 and 6. The β-D-form of this compound is common in cells. Upon entering the cell, most glucose and fructose is converted to fructose 1,6-bisphosphate.
Fructose 6-phosphate is a derivative of fructose, which has been phosphorylated at the 6-hydroxy group. It is one of several possible fructosephosphates. The β-D-form of this compound is very common in cells. The great majority of glucose is converted to fructose 6-phosphate upon entering a cell. Fructose is predominantly converted to fructose 1-phosphate by fructokinase following cellular import.
Fructose 2,6-bisphosphate, abbreviated Fru-2,6-P2, is a metabolite that allosterically affects the activity of the enzymes phosphofructokinase 1 (PFK-1) and fructose 1,6-bisphosphatase (FBPase-1) to regulate glycolysis and gluconeogenesis. Fru-2,6-P2 itself is synthesized and broken down by the bifunctional enzyme phosphofructokinase 2/fructose-2,6-bisphosphatase (PFK-2/FBPase-2).
Fructose-bisphosphate aldolase, often just aldolase, is an enzyme catalyzing a reversible reaction that splits the aldol, fructose 1,6-bisphosphate, into the triose phosphates dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P). Aldolase can also produce DHAP from other (3S,4R)-ketose 1-phosphates such as fructose 1-phosphate and sedoheptulose 1,7-bisphosphate. Gluconeogenesis and the Calvin cycle, which are anabolic pathways, use the reverse reaction. Glycolysis, a catabolic pathway, uses the forward reaction. Aldolase is divided into two classes by mechanism.
The enzyme fructose-2,6-bisphosphate 6-phosphatase (EC 3.1.3.54) catalyzes the reaction
The enzyme phosphatidylinositol-3,4-bisphosphate 4-phosphatase (EC 3.1.3.66) that catalyzes the reaction
The enzyme phosphoinositide 5-phosphatase (EC 3.1.3.36) catalyzes the reaction
Sedoheptulose-bisphosphatase is an enzyme that catalyzes the removal of a phosphate group from sedoheptulose 1,7-bisphosphate to produce sedoheptulose 7-phosphate. SBPase is an example of a phosphatase, or, more generally, a hydrolase. This enzyme participates in the Calvin cycle.
PFKFB3 is a gene that encodes the 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 enzyme in humans. It is one of 4 tissue-specific PFKFB isoenzymes identified currently (PFKFB1-4).
6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 2 is an enzyme that in humans is encoded by the PFKFB2 gene.
Bisphosphate may refer to:
6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 also known as PFKFB4 is an enzyme which in humans is encoded by the PFKFB4 gene.
The TP53-inducible glycolysis and apoptosis regulator (TIGAR) also known as fructose-2,6-bisphosphatase TIGAR is an enzyme that in humans is encoded by the C12orf5 gene.
Fructose-bisphosphatase 2 is an enzyme that in humans is encoded by the FBP2 gene.
