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Pyrophosphate anion.png
Other names
Diphosphate or dipolyphosphate
3D model (JSmol)
E number E450 (thickeners, ...)
PubChem CID
Molar mass 173.943 g·mol−1
Conjugate acid Pyrophosphoric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

In chemistry, pyrophosphates are phosphorus oxyanions that contain two phosphorus atoms in a P-O-P linkage. A number of pyrophosphate salts exist, such as Na2H2P2O7. Often pyrophosphates are called diphosphates. The parent pyrophosphates are derived from partial or complete neutralization of pyrophosphoric acid. Important salts include disodium pyrophosphate and tetrasodium pyrophosphate. The pyrophosphate bond is also sometimes referred to as a phosphoanhydride bond, a naming convention which emphasizes the loss of water that occurs when two phosphates form a new P-O-P bond, and which mirrors the nomenclature for anhydrides of carboylic acids. Pyrophosphates are found in ATP and other nucleotide triphosphates, which are very important in biochemistry.


Pyrophosphates are prepared by heating phosphates, hence the name pyro-phosphate (from the Ancient Greek : πῦρ, πυρός, romanized: pyr, pyros, lit.  'fire' [1] ). More precisely, they are generated by heating phosphoric acids to the extent that a condensation reaction occurs.

Pyrophosphates are generally white or colorless. The alkali metal salts are water-soluble. [2] They are good complexing agents for metal ions (such as calcium and many transition metals) and have many uses in industrial chemistry. Pyrophosphate is the first member of an entire series of polyphosphates. [3]

The term pyrophosphate is also the name of esters formed by the condensation of a phosphorylated biological compound with inorganic phosphate, as for dimethylallyl pyrophosphate. This bond is also referred to as a high-energy phosphate bond.

In biochemistry

The anion P
is abbreviated PPi, standing for inorganic pyrophosphate. It is formed by the hydrolysis of ATP into AMP in cells.


For example, when a nucleotide is incorporated into a growing DNA or RNA strand by a polymerase, pyrophosphate (PPi) is released. Pyrophosphorolysis is the reverse of the polymerization reaction in which pyrophosphate reacts with the 3′-nucleosidemonophosphate (NMP or dNMP), which is removed from the oligonucleotide to release the corresponding triphosphate (dNTP from DNA, or NTP from RNA).

The pyrophosphate anion has the structure P
, and is an acid anhydride of phosphate. It is unstable in aqueous solution and hydrolyzes into inorganic phosphate:

+ H2O → 2 HPO2−

or in biologists' shorthand notation:

PPi + H2O → 2 Pi + 2 H+

In the absence of enzymic catalysis, hydrolysis reactions of simple polyphosphates such as pyrophosphate, linear triphosphate, ADP, and ATP normally proceed extremely slowly in all but highly acidic media. [4]

(The reverse of this reaction is a method of preparing pyrophosphates by heating phosphates.)

This hydrolysis to inorganic phosphate effectively renders the cleavage of ATP to AMP and PPi irreversible, and biochemical reactions coupled to this hydrolysis are irreversible as well.

PPi occurs in synovial fluid, blood plasma, and urine at levels sufficient to block calcification and may be a natural inhibitor of hydroxyapatite formation in extracellular fluid (ECF). [5] Cells may channel intracellular PPi into ECF. [6] ANK is a nonenzymatic plasma-membrane PPi channel that supports extracellular PPi levels. [6] Defective function of the membrane PPi channel ANK is associated with low extracellular PPi and elevated intracellular PPi. [5] Ectonucleotide pyrophosphatase/phosphodiesterase (ENPP) may function to raise extracellular PPi. [6]

From the standpoint of high energy phosphate accounting, the hydrolysis of ATP to AMP and PPi requires two high-energy phosphates, as to reconstitute AMP into ATP requires two phosphorylation reactions.

2 ADP + 2 Pi → 2 ATP

The plasma concentration of inorganic pyrophosphate has a reference range of 0.58–3.78 µM (95% prediction interval). [7]


Isopentenyl pyrophosphate converts to geranyl pyrophosphate the precursor to tens of thousand of terpenes and terpenoids. [8]

Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) condense to produce geranyl pyrophosphate, precursor to all terpenes and terpenoids. Synthesis of geranyl pyrophosphate.png
Isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP) condense to produce geranyl pyrophosphate, precursor to all terpenes and terpenoids.

As a food additive

Various diphosphates are used as emulsifiers, stabilisers, acidity regulators, raising agents, sequestrants, and water retention agents in food processing. [9] They are classified in the E number scheme under E450: [10]

E450(a): disodium dihydrogen diphosphate; trisodium diphosphate; tetrasodium diphosphate (TSPP); tetrapotassium diphosphate
E450(b): pentasodium and pentapotassium triphosphate
E450(c): sodium and potassium polyphosphates

In particular, various formulations of diphosphates are used to stabilize whipped cream. [11]

See also

Related Research Articles

Adenosine triphosphate Chemical compound

Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all forms of life, ATP is often referred to as the "molecular unit of currency" of intracellular energy transfer. When consumed in metabolic processes, it converts either to adenosine diphosphate (ADP) or to adenosine monophosphate (AMP). Other processes regenerate ATP so that the human body recycles its own body weight equivalent in ATP each day. It is also a precursor to DNA and RNA, and is used as a coenzyme.

Hydrolysis is any chemical reaction in which a molecule of water ruptures one or more chemical bonds. The term is used broadly for substitution, elimination, and fragmentation reactions in which water is the nucleophile.

Nucleotide biological molecules that form the building blocks of nucleic acids

Nucleotides are molecules consisting of a nucleoside and a phosphate group. They are the basic building blocks of DNA and RNA.

Phosphate salt or ester of phosphoric acid

In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid H

Adenosine diphosphate chemical compound

Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is essential to the flow of energy in living cells. ADP consists of three important structural components: a sugar backbone attached to adenine and two phosphate groups bonded to the 5 carbon atom of ribose. The diphosphate group of ADP is attached to the 5’ carbon of the sugar backbone, while the adenosine attaches to the 1’ carbon.

Adenosine monophosphate chemical compound

Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine; it is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-.

High-energy phosphate can mean one of two things:

Polyphosphates are salts or esters of polymeric oxyanions formed from tetrahedral PO4 (phosphate) structural units linked together by sharing oxygen atoms. Polyphosphates can adopt linear or a cyclic ring structures. In biology, the polyphosphate esters ADP and ATP are involved in energy storage. A variety of polyphosphates find application in mineral sequestration in municipal waters, generally being present at 1 to 5 ppm. GTP, CTP, and UTP are also nucleotides important in the protein synthesis, lipid synthesis, and carbohydrate metabolism, respectively.

An oxyanion, or oxoanion, is an ion with the generic formula A
. Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound H
. The structures of condensed oxyanions can be rationalized in terms of AOn polyhedral units with sharing of corners or edges between polyhedra. The phosphate and polyphosphate esters adenosine monophosphate (AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology.

A nucleoside triphosphate is a molecule containing a nitrogenous base bound to a 5-carbon sugar, with three phosphate groups bound to the sugar. It is an example of a Nucleotide. They are the building blocks of both DNA and RNA, which are chains of nucleotides made through the processes of DNA replication and transcription. Nucleoside triphosphates also serve as a source of energy for cellular reactions and are involved in signalling pathways.

ATP hydrolysis

ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released by splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate, orthophosphate (Pi). ADP can be further hydrolyzed to give energy, adenosine monophosphate (AMP), and another orthophosphate (Pi). ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction, the establishment of electrochemical gradients across membranes, and biosynthetic processes necessary to maintain life.

Tetrasodium pyrophosphate chemical compound

Tetrasodium pyrophosphate, also called sodium pyrophosphate, tetrasodium phosphate or TSPP, is an inorganic compound with the formula Na4P2O7. As a salt, it is a white, water-soluble solid. It is composed of pyrophosphate anion and sodium ions. Toxicity is approximately twice that of table salt when ingested orally. Also known is the decahydrate Na4P2O7 · 10(H2O).

Phosphoric acids and phosphates

A phosphoric acid, in the general sense, is a phosphorus oxoacid in which each phosphorus atom is in the oxidation state +5, and is bonded to four oxygen atoms, one of them through a double bond, arranged as the corners of a tetrahedron. Two or more of these PO
tetrahedra may be connected by shared single-bonded oxygens, forming linear or branched chains, cycles, or more complex structures. The single-bonded oxygen atoms that are not shared are completed with acidic hydrogen atoms. The general formula of a phosphoric acid is Hn+2−2xPnO3n+1−x, where n is the number of phosphorus atoms and x is the number of fundamental cycles in the molecule's structure, between 0 and (n+2)/2.

Apyrase InterPro Family

Apyrase is a calcium-activated plasma membrane-bound enzyme that catalyses the hydrolysis of ATP to yield AMP and inorganic phosphate. Two isoenzymes are found in commercial preparations from S. tuberosum. One with a higher ratio of substrate selectivity for ATP:ADP and another with no selectivity.

Nucleic acid metabolism

Nucleic acid metabolism is the process by which nucleic acids are synthesized and degraded. Nucleic acids are polymers of nucleotides. Nucleotide synthesis is an anabolic mechanism generally involving the chemical reaction of phosphate, pentose sugar, and a nitrogenous base. Destruction of nucleic acid is a catabolic reaction. Additionally, parts of the nucleotides or nucleobases can be salvaged to recreate new nucleotides. Both synthesis and degradation reactions require enzymes to facilitate the event. Defects or deficiencies in these enzymes can lead to a variety of diseases.

Inorganic pyrophosphatase group of proteins having inorganic pyrophosphatase activity

Inorganic pyrophosphatase is an enzyme that catalyzes the conversion of one ion of pyrophosphate to two phosphate ions. This is a highly exergonic reaction, and therefore can be coupled to unfavorable biochemical transformations in order to drive these transformations to completion. The functionality of this enzyme plays a critical role in lipid metabolism, calcium absorption and bone formation, and DNA synthesis, as well as other biochemical transformations.

Translocase is a general term for a protein that assists in moving another molecule, usually across a cell membrane. These enzymes catalyze the movement of ions or molecules across membranes or their separation within membranes. The reaction is designated as a transfer from “side 1” to “side 2” because the designations “in” and “out”, which had previously been used, can be ambiguous. Translocases are the most common secretion system in Gram positive bacteria.

In enzymology, an ATP diphosphatase (EC is an enzyme that catalyzes the chemical reaction

In enzymology, a polyphosphate kinase, or polyphosphate polymerase, is an enzyme that catalyzes the formation of polyphosphate from ATP, with chain lengths of up to a thousand or more orthophosphate moieties.

A biphosphate is any of the following :


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  11. Ricardo A. Molins, Phosphates in Food, p. 115

Further reading