Oxaloacetic acid

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Template:Chembox ECNumberTemplate:Chembox E number
Oxaloacetic acid
IUPAC name Oxobutanedioic acid
Other names Oxaloacetic acid
Oxalacetic acid
Oxosuccinic acid
Identifiers
3D model (JSmol)
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Properties
C4H4O5
Molar mass 132.07 g/mol
Density ? g/cm3
Melting point
Thermochemistry
Std enthalpy of
formation
ΔfHo298
-943.21 kJ/mol
Std enthalpy of
combustion
ΔcHo298
-1205.58 kJ/mol
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Oxaloacetic acid is an organic compound with the chemical formula HO2CC(O)CH2CO2H. It also has other names (see Table) and its conjugate base is called "oxaloacetate." This four-carbon dicarboxylic acid is a protonated variant of oxaloacetate, which is an intermediate of the citric acid cycle 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.

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). The enol proton has a pKa value of 13.02. The enzyme fumarase A from E. coli catalyses the conversion between the keto and enol forms.

Oxaloacetic acid is unstable in solution, decomposing to pyruvic acid by decarboxylation over a period of hours (room temperature) or days (0 °C). Refrigerated storage of the solid is therefore recommended.

File:Oxaloac-malic.png
Relationship of oxaloacetic acid, malic acid, and aspartic acid


References


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cs:Kyselina oxaloctová de:Oxalessigsäure it:Acido ossalacetico lv:Skābeņetiķskābe hu:Oxálecetsav sv:Oxalättiksyra


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