Inorganic pyrophosphatase

pyrophosphatase (inorganic) 1
Structure of inorganic pyrophosphatase, isolated from Thermococcus litoralis.
Identifiers
Symbol	PPA1
Alt. symbols	PP
Entrez	5464
HUGO	9226
OMIM	179030
RefSeq	NM_021129
UniProt	Q15181
Other data
EC number	3.6.1.1
Locus	Chr. 10 q11.1-q24

Pyrophosphatase (or inorganic pyrophosphatase) is an enzyme (EC 3.6.1.1) that catalyzes the conversion of one molecule 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 (including lipid synthesis and degradation), calcium absorption and bone formation, and DNA synthesis, as well as other biochemical transformations.

Thermostable 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 hexameric oligomeric organization (Image 1). Though the human form of the enzyme has not yet been isolated, a 1.23 kilobase cDNA segment has been identified that encodes a 32 kDa protein that is 94% identical to bovine inorganic pyrophosphatase. This DNA sequence has assigned to a gene locus on human chromosome 10.