Oxaloacetic acid

Oxaloacetic acid is a four-carbon dicarboxylic keto acid that participates in the citric acid cycle, gluconeogenesis, and amino acid metabolism. Its keto group can accept an amino group to form aspartate.

Citrate synthase: Citrate synthase catalyzes the condensation of oxaloacetate and acetyl-CoA to form citrate. This enzyme uses oxaloacetate to begin each turn of the citric acid cycle.
Citric acid cycle: The citric acid cycle oxidizes acetyl-CoA and generates reduced electron carriers for cellular energy production. Oxaloacetate condenses with acetyl-CoA and is regenerated as the cycle proceeds.
Keto acid: A keto acid is an organic acid that contains both a carboxyl group and a ketone carbonyl. Oxaloacetic acid is a four-carbon member of this chemical family.
Acetyl-CoA: Acetyl-CoA is a two-carbon thioester that carries activated acetyl groups into metabolic reactions. Unlike oxaloacetate, it is consumed in the cycle's citrate-forming condensation rather than regenerated there.
Malate dehydrogenase: Malate dehydrogenase catalyzes the reversible conversion of malate and NAD⁺ into oxaloacetate and NADH. This reaction regenerates oxaloacetate at the end of the citric acid cycle.
Gluconeogenesis: Gluconeogenesis is the metabolic pathway that synthesizes glucose from non-carbohydrate precursors. Oxaloacetate is converted toward phosphoenolpyruvate early in this pathway.
Dicarboxylic acid: A dicarboxylic acid is an organic compound containing two carboxyl groups. Oxaloacetic acid has two carboxyl groups, giving it its acidic character.
α-Ketoglutarate: α-Ketoglutarate is a five-carbon dicarboxylic keto acid in the citric acid cycle and amino-acid metabolism. It is another cycle keto acid, but it has five carbons and a different position in the pathway.
Aspartate aminotransferase: Aspartate aminotransferase transfers an amino group between glutamate and oxaloacetate, producing aspartate and α-ketoglutarate. Its reversible reaction links oxaloacetate to amino-acid metabolism.
Anaplerotic reactions: Anaplerotic reactions replenish intermediates removed from the citric acid cycle. Pyruvate carboxylase replenishes the cycle by producing oxaloacetate.

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Malic acidRelated: It is the product formed when malate is oxidized.