Pyrophosphate 105658 191789666 2008-02-16T04:11:07Z VoABot II 1879647 BOT - Reverted edits by [[Special:Contributions/216.17.37.189|216.17.37.189]] {[[User:VoABot_II/Help#Revert_reasons|possible vandalism]]} to last version by [[Special:Contributions/Le Pied-bot|Le Pied-bot]]. [[Image:Pyrophosphate-3D-balls.png|thumb|right|250px|[[Ball-and-stick model]] of the pyrophosphate anion, P<sub>2</sub>O<sub>7</sub><sup>4−</sup>]] In [[chemistry]], the [[anion]], the [[salt]]s, and the [[ester]]s of [[pyrophosphoric acid]] are called '''pyrophosphates'''. The anion P<sub>2</sub>O<sub>7</sub><sup>4−</sup> is abbreviated '''PP<sub>i</sub>''' and is formed by the [[hydrolysis]] of [[Adenosine triphosphate|ATP]] into [[Adenosine monophosphate|AMP]] in [[Cell (biology)|cells]]. * ATP → [[adenosine monophosphate|AMP]] + PP<sub>i</sub> 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 where pyrophosphate reacts with the 3'-nucleotidemonophosphate ([[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<sub>2</sub>O<sub>7</sub><sup>4&minus;</sup>, and is an [[acid]] [[anhydride]] of [[phosphate]]. It is unstable in [[aqueous solution]] and rapidly [[hydrolysis|hydrolyze]]s into inorganic phosphate: * P<sub>2</sub>O<sub>7</sub><sup>4−</sup> + H<sub>2</sub>O → 2 HPO<sub>4</sub><sup>2&minus;</sup> or in shorthand notation: * PP<sub>i</sub> + H<sub>2</sub>O → 2 P<sub>i</sub> This hydrolysis to inorganic phosphate effectively renders the cleavage of ATP to AMP and PP<sub>i</sub> [[hydrolysis|irreversible]], and biochemical reactions coupled to this hydrolysis are irreversible as well. From the standpoint of [[high energy phosphate]] accounting, the hydrolysis of ATP to AMP and PP<sub>i</sub> will require two high energy phosphates, as to reconstitute AMP into ATP will require two phosphorylation reactions. * AMP + ATP → 2 [[Adenosine diphosphate|ADP]] * 2 ADP + 2 P<sub>i</sub> → 2 ATP The synthesis of tetraethyl pyrophosphate was first described in 1854 by Philip de Clermount at a meeting of the French Academy of Sciences. The term '''pyrophosphate''' is also the name of esters formed by the [[condensation reaction|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. == See also == * [[Sodium pyrophosphate]] * [[Calcium pyrophosphate dihydrate deposition disease]] ==External links== * {{MeshName|Pyrophosphates}} [[Category:Phosphates]] [[Category:Pyrophosphates]] [[Category:Oxoanions]] [[de:Diphosphate]] [[es:Pirofosfato]] [[hu:Difoszfátok]] [[pl:Pirofosforan]] [[pt:Pirofosfato]]