Oxaloacetic acid 1110600 212592029 2008-05-15T12:53:42Z AlnoktaBOT 3096998 robot Adding: [[ar:حمض أكسالوأسيتك]] {{Chembox new | Name = Oxaloacetic acid | ImageFile = Oxaloacetic acid.png | ImageName = | IUPACName = Oxobutanedioic acid | OtherNames = Oxaloacetic acid<br />Oxalacetic acid<br />Oxosuccinic acid | Section1 = {{Chembox Identifiers | CASNo = 328-42-7 | EINECS = 206-329-8 | SMILES = OC(C(CC(O)=O)=O)=O }} | Section2 = {{Chembox Properties | Formula = C<sub>4</sub>H<sub>4</sub>O<sub>5</sub> | MolarMass = 132.07 g/mol | MeltingPt = 161 °C | Density = ? g/cm<sup>3</sup> }} | Section4 = {{Chembox Thermochemistry | DeltaHf = -943.21 kJ/mol | DeltaHc = -1205.58 kJ/mol }} }} '''Oxaloacetic acid''' is an [[organic compound]] with the chemical formula HO<sub>2</sub>CC(O)CH<sub>2</sub>CO<sub>2</sub>H. 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-[[Malic acid|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 [[Carbon dioxide|CO<sub>2</sub>]] with [[phosphoenolpyruvate]], catalysed by [[Phosphoenolpyruvate carboxykinase|PEP Carboxykinase]]. It can arise from [[pyruvate]] via an [[anaplerotic reactions|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 [[Acid dissociation constant|pK<sub>a</sub> value]] of 13.02. The [[enzyme]] [[fumarase]] A from [[Escherichia coli|''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. [[Image:Oxaloac-malic.png|thumb|150px|left|Relationship of oxaloacetic acid, malic acid, and aspartic acid]] <br clear = left/> ==References== {{Unreferenced|date =September 2007}} <references/> {{citric acid cycle}} {{metabolism-stub}} [[Category:Citric acid cycle compounds]] [[Category:Dicarboxylic acids]] [[Category:Ketones]] [[ar:حمض أكسالوأسيتك]] [[cs:Kyselina oxaloctová]] [[de:Oxalessigsäure]] [[fr:Acide oxaloacétique]] [[it:Acido ossalacetico]] [[he:אוקסלואצטט]] [[lv:Skābeņetiķskābe]] [[hu:Oxálecetsav]] [[ja:オキサロ酢酸]] [[pl:Kwas szczawiooctowy]] [[pt:Ácido oxaloacético]] [[sv:Oxalättiksyra]]