shikimate

Shikimate is an intermediate in the shikimate pathway, the biosynthetic route by which plants, bacteria, and fungi synthesize the aromatic amino acids phenylalanine, tyrosine, and tryptophan. Chemically, shikimate is a cyclohexene carboxylic acid bearing several hydroxyl groups.

It is not found in animals and is essential to the metabolism of many microbes and plants. The shikimate pathway connects primary metabolism to the production of chorismate, the branch point for downstream aromatic compounds, including the three amino acids and various secondary metabolites.

In the shikimate pathway, 3-dehydroshikimate is reduced to shikimate by shikimate dehydrogenase; shikimate is then phosphorylated by shikimate kinase to form shikimate-3-phosphate. This compound condenses with phosphoenolpyruvate via 5-enolpyruvylshikimate-3-phosphate synthase to yield EPSP (5-enolpyruvylshikimate-3-phosphate), which is subsequently converted to chorismate by chorismate synthase. Chorismate serves as a key precursor for phenylalanine, tyrosine, and tryptophan biosynthesis.

Industrial and research relevance includes the use of shikimate as a starting material for the production of oseltamivir (Tamiflu) and as a biochemical reference in metabolic studies. Shikimic acid can be sourced from plants such as star anise, among other producers. In agriculture, the herbicide glyphosate inhibits EPSP synthase, thereby blocking the pathway in susceptible organisms. Shikimate and its pathway remain central to studies of aromatic amino acid biosynthesis and metabolic engineering.