oxaloacetate
Noun
Meaning
a salt or ester of oxalacetic acid
Source: WordNetSynonyms
Hypernyms
Examples
De-aminated alanine, cysteine, glycine, serine, and threonine are converted to pyruvate and can consequently either enter the citric acid cycle as oxaloacetate (an anaplerotic reaction) or as acetyl-CoA to be disposed of as CO 2 and water.
Below is a schematic outline of the cycle: * The citric acid cycle begins with the transfer of a two-carbon acetyl group from acetyl-CoA to the four-carbon acceptor compound (oxaloacetate) to form a six-carbon compound (citrate).
During gluconeogenesis mitochondrial oxaloacetate is reduced to malate which is then transported out of the mitochondrion, to be oxidized back to oxaloacetate in the cytosol.
In the liver, therefore, oxaloacetate is unavailable for condensation with acetyl-CoA when significant gluconeogenesis has been stimulated by low (or absent) insulin and high glucagon concentrations in the blood.
Other biological roles Citrate can be transported out of the mitochondria and into the cytoplasm, then broken down into acetyl-CoA for fatty acid synthesis and into oxaloacetate.
A transaminase converts the oxaloacetate to aspartate for transport back across the membrane and into the intermembrane space.