(also phosphopyruvic acid), a high-energy compound that is an important metabolic intermediate in animals, plants, and microorganisms. The acid’s structural formula is

Phosphoenolpyruvic acid is formed during glycolysis from 2-phosphoglyceric acid upon the separation of a water molecule from the latter under the action of the enzyme enolase; it is also formed from oxalacetic acid upon decarboxylation, which is accompanied by the transfer of the phosphoryl group (—H₂PO₃) from nucleoside triphosphates to the pyruvic acid that is being formed.

Phosphoenolpyruvic acid is easily hydrolyzed in aqueous solutions to yield phosphoric and pyruvic acids. It figures in the biosynthesis of adenosine triphosphate, which is formed with the transfer of a phosphoryl group from phosphoenolpyruvic acid to adenosine diphosphate; the transfer results from a reaction catalyzed by the enzyme pyruvate kinase. Phosphoenolpyruvic acid is present in cells in an ionized form known as phosphoenolpyruvate.