Alanine

An amino acid(CH3·CH·NH2·COOH, molecular weight 89.1) found in protein. It can be synthesized in the body from pyruvate and an amino donor such as glutamic acid. Substantial quantities of alanine are synthesized in gut mucosa and muscle, and the alanine not used for protein synthesis is transported to the liver where the enzyme alanine aminotransferase converts alanine to pyruvate. Mitochondrial pyruvate in the liver can either be used in the TCA cycle, or it can be converted (carboxylated) to oxaloacetate, some of which is subsequently reduced to malate, some transaminated to aspartate, and some decarboxylated to phosphoenolpyruvate. All three of these compounds can escape the mitochondrion and enter the cytosol to be used for gluconeogenesis. Integration of these processes involving muscle and liver tissue is often referred to as the glucose–alanine cycle.