Inorganic pyrophosphatase (or inorganic diphosphatase, PPase) is an enzyme (EC 3.6.1.1) that catalyzes the conversion of one ion of pyrophosphate to two phosphate ions.[1] This is a highly exergonicreaction, and therefore can be coupled to unfavorable biochemical transformations in order to drive these transformations to completion.[2] The functionality of this enzyme plays a critical role in lipid metabolism(including lipid synthesis and degradation), calcium absorption and bone formation,[3][4] and DNA synthesis,[5] as well as other biochemical transformations.[6][7]
Two types of inorganic diphosphatase, very different in terms of both amino acid sequence and structure, have been characterised to date: soluble and transmembrane proton-pumping pyrophosphatases(sPPases and H(+)-PPases, respectively). sPPases are ubiquitous proteins that hydrolyse pyrophosphateto release heat, whereas H+-PPases, so far unidentified in animal and fungal cells, couple the energy of PPi hydrolysis to proton movement across biological membranes.[8][9]
| inorganic pyrophosphatase | |
|---|---|
 Pyrophosphatase (inorganic) hexamer, E.Coli |
Thermostable soluble pyrophosphatase had been isolated from the extremophile Thermococcus litoralis. The 3-dimensional structure was determined using x-ray crystallography, and was found to consist of two alpha-helices, as well as an antiparallel closed beta-sheet. The form of inorganic pyrophosphatase isolated from Thermococcus litoralis was found to contain a total of 174 amino acid residues and have a hexamericoligomeric organization (Image 1).[10]
Humans possess two genes encoding pyrophosphatase, PPA1 and PPA2.[11] PPA1 has been assigned to a gene locus on human chromosome 10,[12] and PPA2 to chromosome 4.[13]
https://en.wikipedia.org/wiki/Inorganic_pyrophosphatase
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