A three-carbon carboxylic keto acid with the formula CH3
COCO OH. In glucose metabolism pyruvate is an intermediate in glycolysis. Under anaerobic conditions it is reduced to form ethanol or some other fermentation product, while in aerobic conditions it is decarboxylated to form acetyl CoA. In C4 plants pyruvate is an intermediate of the Hatch-Slack pathway. In amino acid metabolism pyruvate is the degradation product of several amino acids, including alanine and cysteine, while other amino acids are synthesized from pyruvate. Pyruvate can also be carboxylated to form oxaloacetate or malate, both intermediates in the *TCA cycle
. These reactions, known as anaplerotic reactions, replenish TCA cycle intermediates.