09-04-2021-1613 - 3-Phosphoglyceric acid (3PG, 3-PGA, or PGA) is the conjugate acid of 3-phosphoglycerate or glycerate 3-phosphate (GP or G3P). 820111

3-Phosphoglyceric acid (3PG, 3-PGA, or PGA) is the conjugate acid of 3-phosphoglycerate or glycerate 3-phosphate (GP or G3P).^[1] This glycerate is a biochemically significant metabolic intermediate in both glycolysis and the Calvin-Benson cycle. The anion is often termed as PGA when referring to the Calvin-Benson cycle. In the Calvin-Benson cycle, 3-phosphoglycerate is typically the product of the spontaneous scission of an unstable 6-carbon intermediate formed upon CO₂ fixation. Thus, two equivalents of 3-phosphoglycerate are produced for each molecule of CO₂that is fixed.^[2][3][4] In glycolysis, 3-phosphoglycerate is an intermediate following the dephosphorylation (reduction) of 1,3-bisphosphoglycerate.^[4]:14​ 

3-Phosphoglyceric acidNamesIUPAC name

(2R)-2-Hydroxy-3-phosphonooxypropanoic acid

Identifiers

CAS Number

• 820-11-1 
  3D model (JSmol)
  • Interactive image
  3DMet
  • C00197
  ChEBI
  • CHEBI:17794 ChEMBL
    • ChEMBL1160563 ChemSpider
      • 388326 DrugBank
        • DB04510
        KEGG
        • C00197
        PubChem CID
        • 439183
        CompTox Dashboard (EPA)
        • DTXSID601002368 
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        InChI
        show

        SMILES
        Properties
        Chemical formula
        C₃H₇O₇PMolar mass186.06 g/mol

n the glycolytic pathway, 1,3-bisphosphoglycerate is dephosphorylated to form 3-phosphoglyceric acid in a coupled reaction producing two ATP via substrate-level phosphorylation.^[5] The single phosphate group left on the 3-PGA molecule then moves from an end carbon to a central carbon, producing 2-phosphoglycerate.^[5][a]This phosphate group relocation is catalyzed by phosphoglycerate mutase, an enzyme that also catalyzes the reverse reaction.^[6]

In the light-independent reactions (also known as the Calvin-Benson cycle), two 3-phosphoglycerate molecules are synthesized. RuBP, a 5-carbon sugar, undergoes carbon fixation, catalyzed by the rubisco enzyme, to become an unstable 6-carbon intermediate. This intermediate is then cleaved into two, separate 3-carbon molecules of 3-PGA.^[7] One of the resultant 3-PGA molecules continues through the Calvin-Benson cycle to be regenerated into RuBP while the other is reduced to form one molecule of glyceraldehyde 3-phosphate (G3P) in two steps: the phosphorylation of 3-PGA into 1,3-bisphosphoglyceric acid via the enzyme phosphoglycerate kinase (the reverse of the reaction seen in glycolysis) and the subsequent catalysis by glyceraldehyde 3-phosphate dehydrogenase into G3P.^[8][9][10] G3P eventually reacts to form the sugars such as glucose or fructose or more complex starches.^[4]:156​^[8][9]

Glycerate 3-phosphate (formed from 3-phosphoglycerate) is also a precursor for serine, which, in turn, can create cysteine and glycine through the homocysteine cycle.^[11][12][13]

https://en.wikipedia.org/wiki/3-Phosphoglyceric_acid