Oxaloacetic acid
Oxaloacetic acid (also known as oxalacetic acid) is a crystalline organic compound with the chemical formula HO2CC(O)CH2CO2H. Oxaloacetic acid, in the form of its conjugate base oxaloacetate, is a metabolic intermediate in many processes that occur in animals. It takes part in the: gluconeogenesis, urea cycle, glyoxylate cycle, amino acid synthesis, fatty acid synthesis and citric acid cycle.
Properties
Oxaloacetic acid undergoes successive deprotonations to give the dianion:
At high pH, the enolizable proton is ionized:
The enol forms of oxaloacetic acid are particularly stable, so much so that the two tautomer have different melting points (152 °C for the cis isoform and 184 °C for the trans isoform).
Biosynthesis
Oxaloacetate forms in several ways in nature. A principal route is upon oxidation of L-malate, catalysed by malate dehydrogenase, in the citric acid cycle. Malate is also oxidized by succinate dehydrogenase in a slow reaction with the initial product being enol-oxaloacetate.
It also arises from the condensation of pyruvate with carbonic acid, driven by the hydrolysis of ATP:
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