3-Phosphoglyceric acid explained

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 CO2 that is fixed.[2] [3] [4] In glycolysis, 3-phosphoglycerate is an intermediate following the dephosphorylation (reduction) of 1,3-bisphosphoglycerate.

Glycolysis

See main article: Glycolysis. In 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. This phosphate group relocation is catalyzed by phosphoglycerate mutase, an enzyme that also catalyzes the reverse reaction.[6]

1,3-bisphospho--glycerate3-phosphoglycerate kinase3-phospho--glyceratePhosphoglyceromutase2-phospho--glycerate
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ADPATP
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ADPATP
  
 3-phosphoglycerate kinase Phosphoglyceromutase

Calvin-Benson cycle

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.

Amino acid synthesis

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]

Measurement

3-phosphoglycerate can be separated and measured using paper chromatography[14] as well as with column chromatography and other chromatographic separation methods.[15] It can be identified using both gas-chromatography and liquid-chromatography mass spectrometry and has been optimized for evaluation using tandem MS techniques.[16] [17]

See also

Notes and References

  1. Web site: Human Metabolome Database . 3-Phosphoglyceric acid (HMDB0000807) . The Metabolomics Innovation Centre . 23 May 2021.
  2. Book: Berg . J.M. . Tymoczko . J.L. . Stryer . L. . Biochemistry . 2002 . 5th . . New York . 0-7167-3051-0 . registration .
  3. Book: Nelson . D.L. . Cox . M.M. . Lehninger, Principles of Biochemistry . 3rd . Worth Publishing . New York . 2000 . 1-57259-153-6.
  4. Book: Photosynthesis: Physiology and Metabolism . Leegood . R.C. . Sharkey . T.D. . von Caemmerer . S. . 2000 . Kluwer Academic Publishers . Advances in Photosynthesis . 9 . 978-0-7923-6143-5 . 10.1007/0-306-48137-5 . 266763949 .
  5. Book: Connie . Rye . Robert . Wise . Vladimir . Jurukovski . Jean . DeSaix . Jung . Choi . Yael . Avissar . Biology . OpenStax College . Glycolysis . https://openstax.org/books/biology/pages/7-2-glycolysis . 2016.
  6. Rates of phosphorylation and dephosphorylation of phosphoglycerate mutase and bisphosphoglycerate synthase . Rose . Z.B. . Dube . S. . Journal of Biological Chemistry . 1976 . 251 . 16 . 4817–4822 . 10.1016/S0021-9258(17)33188-5 . 8447. free .
  7. Andersson . I. . Catalysis and regulation in Rubisco . Journal of Experimental Botany . 59 . 7 . 2008 . 1555–1568 . 10.1093/jxb/ern091 . 18417482. free .
  8. Web site: Moran . L. . 2007 . The Calvin Cycle: Regeneration . Sandwalk . 11 May 2021.
  9. Pettersson . G. . Ryde-Pettersson . Ulf . A mathematical model of the Calvin photosynthesis cycle . European Journal of Biochemistry . 175 . 3 . 661–672 . 1988 . 10.1111/j.1432-1033.1988.tb14242.x . 3137030. free .
  10. Regulation of the Calvin cycle for CO2 fixation as an example for general control mechanisms in metabolic cycles . Fridlyand . L.E. . Scheibe . R. . Biosystems . 51 . 2 . 1999 . 79–93 . 10.1016/S0303-2647(99)00017-9 . 10482420.
  11. Igamberdiev . A.U. . Kleczkowski . L.A. . The Glycerate and Phosphorylated Pathways of Serine Synthesis in Plants: The Branches of Plant Glycolysis Linking Carbon and Nitrogen Metabolism . Frontiers in Plant Science . 9 . 318 . 10.3389/fpls.2018.00318 . 2018 . 318 . 29593770. 5861185 . free .
  12. Ichihara . A. . Greenberg . D.M. . Pathway of Serine Formation from Carbohydrate in Rat Liver . PNAS . 1955 . 41 . 9 . 605–609 . 10.1073/pnas.41.9.605 . 89140 . 16589713. 528146 . 1955PNAS...41..605I . free.
  13. Formation of Phosphoserine from 3-Phosphoglycerate in Higher Plants . Hanford . J. . Davies . D.D. . Nature . 1958 . 182 . 4634 . 532–533 . 10.1038/182532a0. 1958Natur.182..532H . 4192791 .
  14. Cowgill . R.W. . Pizer . L.I. . Purification and Some Properties of Phosphorylglyceric Acid Mutase from Rabbit Skeletal Muscle . Journal of Biological Chemistry . 223 . 2 . 1956 . 885–895 . 10.1016/S0021-9258(18)65087-2 . 13385236. free.
  15. Hofer . H.W. . Separation of glycolytic metabolites by column chromatography . Analytical Biochemistry . 1974 . 61 . 1 . 54–61 . 10.1016/0003-2697(74)90332-7 . 4278264.
  16. Shibayama . J. . Yuzyuk . T.N. . Cox . J. . etal . Metabolic Remodeling in Moderate Synchronous versus Dyssynchronous Pacing-Induced Heart Failure: Integrated Metabolomics and Proteomics Study . PLOS ONE . 2015 . 10 . 3 . e0118974 . 10.1371/journal.pone.0118974 . 25790351. 4366225 . 2015PLoSO..1018974S . free .
  17. Xu . J. . Zhai . Y. . Feng . L. . An optimized analytical method for cellular targeted quantification of primary metabolites in tricarboxylic acid cycle and glycolysis using gas chromatography-tandem mass spectrometry and its application in three kinds of hepatic cell lines . Journal of Pharmaceutical and Biomedical Analysis . 171 . 2019 . 171–179 . 10.1016/j.jpba.2019.04.022. 31005043 . 125170446.

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