Oxaloacetic acid
Oxaloacetic acid
Identifiers
CAS number 328-42-7 YesY
PubChem 970
ChemSpider 945 YesY
EC number 206-329-8
ChEBI CHEBI:30744 YesY
Jmol-3D images Image 1
Properties
Molecular formula C4H4O5
Molar mass 132.07 g/mol
Density  ? g/cm3
Melting point

161 °C

Thermochemistry
Std enthalpy of
formation
ΔfHo298
-943.21 kJ/mol
Std enthalpy of
combustion
ΔcHo298
-1205.58 kJ/mol
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Oxaloacetic acid (also oxalacetic acid) is an organic compound with the chemical formula C4H4O5 or HOOC-(C=O)-(CH2)-COOH. It also has other names (see the table).

Its fully deprotonated derivative is the oxaloacetate anion, C4H2O52− or [(C=O)2(CH2)(C=O)]2−; this name is also used for esters that contain the divalent [-O(C=O)2(CH2)(C=O)O-] moiety. Loss of a single proton gives the acid's conjugate base, the anion hydrogenoxaloacetate anion H(C=O)2(CH2)(C=O).

Contents

Function

This four-carbon dicarboxylic acid is a protonated variant of oxaloacetate, which is an intermediate of the citric acid cycle[1] and gluconeogenesis. Oxaloacetate forms upon oxidation of L-malate, catalysed by malate dehydrogenase, and reacts with Acetyl-CoA to form citrate, catalysed by citrate synthase. It also forms in the mesophyll of plants by the condensation of CO2 with phosphoenolpyruvate, catalysed by PEP Carboxykinase. It can arise from pyruvate via an anaplerotic reaction. Oxaloacetate is also a potent inhibitor of Complex II.

Relationship of oxaloacetic acid, malic acid, and aspartic acid

Chemical properties

The enol forms of oxaloacetic acid are particularly stable, so much so that the two isomers have different melting points (152 °C cis, 184 °C trans).[clarification needed] The enol proton has a pKa value of 13.02.

Oxaloacetate is unstable in solution, decomposing to pyruvate by decarboxylation over a period of hours (room temperature) or days (0 °C).[citation needed] Refrigerated storage of the solid is therefore recommended.

Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles.[2]

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Citric_acid_cycle edit

See also

References