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Phosphofructokinase

 

 
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Phosphofructokinase
 
 
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Phosphofructokinase-1 (PFK-1) is the most important regulatory enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
  of glycolysis
Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
. It is an allosteric enzyme made of 4 subunits and controlled by several activator
Activator

Activator may mean:* Activator , a DNA-binding protein that regulates one or more genes by increasing the rate of transcription* Activator , a type of effector that increases the rate of enzyme mediated reactions...
s and inhibitor
Enzyme inhibitor

Enzyme inhibitors are molecules that bind to enzymes and decrease their enzyme activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolism imbalance, many drugs are enzyme inhibitors....
s. PFK-1 catalyzes one of the important "committed" steps of glycolysis
Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
, the conversion of fructose 6-phosphate
Fructose 6-phosphate

Fructose 6-phosphate is fructose sugar phosphorylated on carbon 6 . The ?-D-form of this compound is very common in cell . The vast majority of glucose and fructose entering a cell will become converted to this at some point....
 and ATP
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
 to fructose 1,6-bisphosphate and ADP
Adenosine diphosphate

Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine....
.

This step is subject to extensive regulation since it is not only irreversible, but also because the original substrate is forced to proceed down the glycolytic pathway after this step.






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Encyclopedia


Phosphofructokinase-1 (PFK-1) is the most important regulatory enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
  of glycolysis
Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
. It is an allosteric enzyme made of 4 subunits and controlled by several activator
Activator

Activator may mean:* Activator , a DNA-binding protein that regulates one or more genes by increasing the rate of transcription* Activator , a type of effector that increases the rate of enzyme mediated reactions...
s and inhibitor
Enzyme inhibitor

Enzyme inhibitors are molecules that bind to enzymes and decrease their enzyme activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolism imbalance, many drugs are enzyme inhibitors....
s. PFK-1 catalyzes one of the important "committed" steps of glycolysis
Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
, the conversion of fructose 6-phosphate
Fructose 6-phosphate

Fructose 6-phosphate is fructose sugar phosphorylated on carbon 6 . The ?-D-form of this compound is very common in cell . The vast majority of glucose and fructose entering a cell will become converted to this at some point....
 and ATP
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
 to fructose 1,6-bisphosphate and ADP
Adenosine diphosphate

Adenosine diphosphate, abbreviated ADP, is a nucleotide. It is an ester of pyrophosphoric acid with the nucleoside adenosine. ADP consists of the pyrophosphate Functional group, the pentose sugar ribose, and the nucleobase adenine....
.

This step is subject to extensive regulation since it is not only irreversible, but also because the original substrate is forced to proceed down the glycolytic pathway after this step. This leads to a precise control of glucose and the other monosaccharide
Monosaccharide

Monosaccharides are the most basic unit of carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystal solids....
s galactose
Galactose

Galactose is a type of Carbohydrate which is less sweetness than glucose. It is considered a nutritive sweetener because it has food energy.Galactan is a polymer of the sugar galactose....
 and fructose
Fructose

Fructose is a simple Reducing sugar sugar found in many foods and is one of the three important dietary monosaccharides along with glucose and galactose....
 going down the glycolysis pathway. Before this enzyme's reaction, glucose-6-phosphate
Glucose-6-phosphate

Glucose 6-phosphate is glucose sugar phosphorylated on carbon 6. This compound is very common in cell as the vast majority of glucose entering a cell will become phosphorylated in this way....
 can potentially travel down the pentose phosphate pathway
Pentose phosphate pathway

The pentose phosphate pathway is a process that serves to generate NADPH and the synthesis of pentose sugars. There are two distinct phases in the pathway....
, or be converted to glucose-1-phosphate and polymerized into the storage form Glycogen.

Regulation

PFK1 is allosterically inhibited by ATP
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
 and citrate (from the citric acid cycle
Citric acid cycle

The citric acid cycle ? also known as the tricarboxylic acid cycle ; the Krebs cycle; or, more rarely, the Szent-Gy?rgyi-Krebs cycle) ? is a series of enzyme-catalysed chemical reactions of central importance in all living cell s that use oxygen as part of cellular respiration....
) and its product. It is also inhibited by low pH to prevent the accumulation of hydrogen ions in muscle. The enzyme has two sites with different affinities for ATP which is both a substrate
Substrate (biochemistry)

In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalysis chemical reactions involving the substrate. The substrate binds with the enzyme active site, and an enzyme-substrate complex is formed....
 and an inhibitor.

PFK1 is allosterically activated by a high concentration of AMP
Adenosine monophosphate

Adenosine monophosphate , also known as 5'-adenylic acid, is a nucleotide that is found in RNA. It is an ester of phosphoric acid and the nucleoside adenosine....
, but the most potent activator is fructose 2,6-bisphosphate
Fructose 2,6-bisphosphate

Fructose 2,6-bisphosphate , abbreviated Fru-2,6-P2, is a metabolite which allosterically affects the activity of the enzymes phosphofructokinase 1 and fructose 1,6-bisphosphatase to regulate glycolysis and gluconeogenesis....
, which is also produced from fructose-6-phosphate by PFK2
PFK2

Phosphofructokinase-2 is one activity of a bifunctional enzyme , the other of which is fructose 2,6-bisphosphatase . When serine 32 is phosphorylated, the negative charge causes the conformation of the enzyme to favor the FBPase2 activity....
.

PFK is inhibited by glucagon
Glucagon

Glucagon is an important hormone involved in carbohydrate metabolism. Produced by the pancreas, it is released when the glucose level in the blood is low , causing the liver to convert stored glycogen into glucose and release it into the bloodstream....
 through repression of synthesis.

The precise regulation of PFK 1 prevents glycolysis
Glycolysis

Glycolysis is the metabolic pathway that converts glucose, C6H12O6, into pyruvate, C3H5O3-....
 and gluconeogenesis
Gluconeogenesis

Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactic acid, glycerol, and glucogenic amino acids....
 from occurring simultaneously.

Genes

There are three phosphofructokinase genes in humans: - liver
Liver

The liver is a vital organ present in vertebrates and some other animals; it has a wide range of functions, a few of which are detoxification, protein synthesis, and production of biochemicals necessary for digestion....
 - muscle
MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
 - platelet
Platelet

Platelets, or Thrombocyte, are small, irregularly shaped anuclear cells, 2-4?m in diameter, which are derived from fragmentation of precursor megakaryocytes....


See also

  • PFK2
    PFK2

    Phosphofructokinase-2 is one activity of a bifunctional enzyme , the other of which is fructose 2,6-bisphosphatase . When serine 32 is phosphorylated, the negative charge causes the conformation of the enzyme to favor the FBPase2 activity....
     (converts fructose 6-phosphate to fructose 2,6-bisphosphate through on site, or the opposite, on another site)
  • PFP
    PFP (enzyme)

    PFP or Pyrophosphate:Fructose 6-phosphate Phosphotransferase is an enzyme of carbohydrate metabolism in plants and some bacterium. The enzyme catalyses the reversible interconversion of fructose 6-phosphate and fructose 1,6-bisphosphate using inorganic pyrophosphate as the phosphoryl donor....
     (reversibly interconverts fructose 6-phosphate and fructose 1,6-bisphosphate using inorganic pyrophosphate
    Pyrophosphate

    In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. Pyrophosphates were originally prepared by heating phosphates: the prefix pyro- derived from Greek, means "fire" in this context....
     (rather than ATP)
  • fructose bisphosphatase
    Fructose bisphosphatase

    Fructose bisphosphatase is an enzyme in the liver, that converts fructose-1,6-bisphosphate to fructose 6-phosphate in gluconeogenesis . Fructose bisphosphatase does the opposite job as phosphofructokinase, and both these enzymes only work in one direction....
     (hydrolyses fructose 1,6-bisphosphate to fructose 6-phosphate)


External links