AskDefine | Define oxaloacetate

Dictionary Definition

oxaloacetate n : a salt or ester of oxalacetic acid [syn: oxalacetate]

User Contributed Dictionary

English

Noun

oxaloacetate
  1. any salt or ester of oxaloacetic acid

Extensive Definition

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

References

oxaloacetate in Arabic: حمض أكسالوأسيتك
oxaloacetate in Czech: Kyselina oxaloctová
oxaloacetate in German: Oxalessigsäure
oxaloacetate in French: Acide oxaloacétique
oxaloacetate in Italian: Acido ossalacetico
oxaloacetate in Hebrew: אוקסלואצטט
oxaloacetate in Latvian: Skābeņetiķskābe
oxaloacetate in Hungarian: Oxálecetsav
oxaloacetate in Japanese: オキサロ酢酸
oxaloacetate in Polish: Kwas szczawiooctowy
oxaloacetate in Portuguese: Ácido oxaloacético
oxaloacetate in Swedish: Oxalättiksyra
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