Pyrophosphate
|
WikiDoc Resources for Pyrophosphate |
|
Articles |
|---|
|
Most recent articles on Pyrophosphate Most cited articles on Pyrophosphate |
|
Media |
|
Powerpoint slides on Pyrophosphate |
|
Evidence Based Medicine |
|
Clinical Trials |
|
Ongoing Trials on Pyrophosphate at Clinical Trials.gov Trial results on Pyrophosphate Clinical Trials on Pyrophosphate at Google
|
|
Guidelines / Policies / Govt |
|
US National Guidelines Clearinghouse on Pyrophosphate NICE Guidance on Pyrophosphate
|
|
Books |
|
News |
|
Commentary |
|
Definitions |
|
Patient Resources / Community |
|
Patient resources on Pyrophosphate Discussion groups on Pyrophosphate Patient Handouts on Pyrophosphate Directions to Hospitals Treating Pyrophosphate Risk calculators and risk factors for Pyrophosphate
|
|
Healthcare Provider Resources |
|
Causes & Risk Factors for Pyrophosphate |
|
Continuing Medical Education (CME) |
|
International |
|
|
|
Business |
|
Experimental / Informatics |
Editor-In-Chief: Henry A. Hoff
In chemistry, the anion, the salts, and the esters of pyrophosphoric acid are called pyrophosphates. The anion P2O74− is abbreviated PPi and is formed by the hydrolysis of ATP into AMP in cells.
- ATP → AMP + PPi
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 P2O74−, and is an acid anhydride of phosphate. It is unstable in aqueous solution and in the absence of enzymic catalysis hydrolyzes extremely slowly into inorganic phosphate in all but highly acidic media:[1]
- P2O74− + H2O → 2 HPO42−
or in shorthand notation:
- PPi + H2O → 2 Pi
Enzyme EC 3.6.1.1 catalyzes this hydrolysis.[2] Specificity varies with the source and with the activating metal ion, e.g. Mg2+.[2]
This hydrolysis to inorganic phosphate effectively renders the cleavage of ATP to AMP and PPi ultimately irreversible, and biochemical reactions coupled to this hydrolysis are irreversible as well, unless EC 3.6.1.1 is present. EC 3.6.1.1 can reverse the hydrolysis.[2]
From the standpoint of high energy phosphate accounting, the hydrolysis of ATP to AMP and PPi will require two high energy phosphates, as to reconstitute AMP into ATP will require two phosphorylation reactions.
- AMP + ATP → 2 ADP
- 2 ADP + 2 Pi → 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 of a phosphorylated biological compound with inorganic phosphate as for dimethylallyl pyrophosphate. This bond is also referred to as a high energy phosphate bond.
References
- ↑ Huebner PWA, Milburn RM (1980). "Hydrolysis of pyrophosphate to orthophosphate promoted by cobalt(III). Evidence for the role of polynuclear species". Inorg Chem. 19 (5): 1267–72. doi:10.1021/ic50207a032. Unknown parameter
|month=ignored (help) - ↑ 2.0 2.1 2.2 "NiceZyme View of ENZYME: EC 3.6.1.1".
See also
External links
- Pyrophosphates at the US National Library of Medicine Medical Subject Headings (MeSH)