A principal route is upon oxidation of L-malate, catalyzed 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.

Gluconeogenesis[1] is a metabolic pathway consisting of a series of eleven enzyme-catalyzed reactions, resulting in the generation of glucose from non-carbohydrates substrates.

The beginning of this process takes place in the mitochondrial matrix, where pyruvate molecules are found.

Oxaloacetate is later decarboxylated and phosphorylated by phosphoenolpyruvate carboxykinase and becomes 2-phosphoenolpyruvate using guanosine triphosphate (GTP) as phosphate source.

[4] It is an anabolic pathway occurring in plants and bacteria utilizing the enzymes isocitrate lyase and malate synthase.

[1] This means that oxaloacetate in this cycle also acts as the primary reactant and final product.

In previous stages acetyl-CoA is transferred from the mitochondria to the cytoplasm where fatty acid synthase resides.

The overall reaction, which is spontaneous, may be summarized as: Six essential amino acids and three nonessential are synthesized from oxaloacetate and pyruvate.

These are nonessential amino acids, and their simple biosynthetic pathways occur in all organisms.

Methionine, threonine, lysine, isoleucine, valine, and leucine are essential amino acids in humans and most vertebrates.