Isocitric acid

Isocitric acid
Names
IUPAC name
1-Hydroxypropane-1,2,3-tricarboxylic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.005.713 Edit this at Wikidata
KEGG
MeSH Isocitrate
UNII
  • InChI=1S/C6H8O7/c7-3(8)1-2(5(10)11)4(9)6(12)13/h2,4,9H,1H2,(H,7,8)(H,10,11)(H,12,13) checkY
    Key: ODBLHEXUDAPZAU-UHFFFAOYSA-N checkY
  • InChI=1/C6H8O7/c7-3(8)1-2(5(10)11)4(9)6(12)13/h2,4,9H,1H2,(H,7,8)(H,10,11)(H,12,13)
    Key: ODBLHEXUDAPZAU-UHFFFAOYAX
  • O=C(O)C(CC(=O)O)C(O)C(=O)O
Properties
C6H8O7
Molar mass 192.124
Melting point 105 °C (221 °F; 378 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X markN verify (what is checkYX markN ?)

Isocitric acid is a structural isomer of citric acid and consequently shares similar physical and chemical properties. This makes it difficult to separate the two isomers. Isocitric acid can form salts and esters known as isocitrates. Its anion form is an intermediate in the citric acid cycle.

Isocitric acid is commonly used as a marker to detect the authenticity and quality of fruit products, most often citrus juices. In authentic orange juice, for example, the ratio of citric acid to D-isocitric acid is usually less than 130. An isocitric acid value higher than this may be indicative of fruit juice adulteration.

Isocitric acid has largely been used as a biochemical agent due to limited amounts. However, isocitric acid has been shown to have pharmaceutical and therapeutic effects. Isocitric acid has been shown to effectively treat iron deficient anemia. Additionally, isocitric acid could be used to treat Parkinson's disease. Yarrowia lipolytica can be used to produce isocitric acid and is inexpensive compared to other methods. Furthermore, other methods produce unequal amounts of citric acid to isocitric acid ratio, mostly producing citric acid. Use of Yarrowia lipolytica produces a better yield, making equal amounts of citric acid to isocitric acid.

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.

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TCACycle_WP78 edit
  1. ↑ The interactive pathway map can be edited at WikiPathways: "TCACycle_WP78".

Biochemistry

Citric Acid Cycle

Isocitrate is the intermediate in the citric acid cycle between citrate and α-ketoglutarate. Citrate covalently interacts with the iron-sulfur core of aconitase. The enzyme's core also controls the reversible addition or removal of H2O from the molecule. In the transition between citrate and isocitrate, H2O is temporarily added to the substrate to create the intermediate molecule, cis-aconitate. The intermediate can exist as aconitic acid, but in the citric acid cycle, it does not dissociate from the enzyme and proceeds directly to the next structure when H2O is removed from the molecule. Although the ΔG′°=13.3 kJ/mol, an unfavorable value, the isocitrate concentration is constantly lowered by its transformation into α-ketoglutarate. The transformation between isocitrate and α-ketoglutarate has an intermediate, the enol, oxalosuccinate and is catalyzed by isocitrate dehydrogenase. The enzyme contains an Mn2+ which stabilizes and interacts with the intermediate. After isocitrate is oxidized into oxalosuccinate, it is decarboxylated and rearranged into α-ketoglutarate and continues in the citric acid cycle.

See also

References

  1. 1 2 Kamzolova, Svetlana V.; Morgunov, Igor G. (2019-12-01). "Microbial production of (2R,3S)-isocitric acid: state of the arts and prospects". Applied Microbiology and Biotechnology. 103 (23): 9321–9333. doi:10.1007/s00253-019-10207-4. ISSN 1432-0614. PMID 31748825.
  2. ↑ Saavedra, L.; Garcia, A.; Barbas, C. (9 June 2000). "Development and validation of a capillary electrophoresis method for direct measurement of isocitric, citric, tartaric and malic acids as adulteration markers in orange juice". Journal of Chromatography A. 881 (1–2): 395–401. doi:10.1016/s0021-9673(00)00258-2. PMID 10905722.
  3. 1 2 3 Yuzbasheva, Evgeniya Y.; Scarcia, Pasquale; Yuzbashev, Tigran V.; Messina, Eugenia; Kosikhina, Iuliia M.; Palmieri, Luigi; Shutov, Artem V.; Taratynova, Maria O.; Amaro, Rodrigo Ledesma; Palmieri, Ferdinando; Sineoky, Sergey P. (2021-05-01). "Engineering Yarrowia lipolytica for the selective and high-level production of isocitric acid through manipulation of mitochondrial dicarboxylate–tricarboxylate carriers". Metabolic Engineering. 65: 156–166. doi:10.1016/j.ymben.2020.11.001. hdl:11586/349079. ISSN 1096-7176. PMID 33161142. S2CID 226286865.
  4. ↑ "BenchChem". www.benchchem.com. Retrieved 2026-10-15.
  5. ↑ Nelson, David L. (2021). Lehninger Principles of Biochemistry (8 ed.). Macmillan Learning. pp. 2106–2119. ISBN 9781319230906.