Chorismic acid
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Chorismic acid, more commonly known as its anionic form chorismate, is an important biochemical intermediate in plants and microorganisms. It is a precursor for:
- The aromatic amino acids phenylalanine, tryptophan, and tyrosine
- Indole, indole derivatives and tryptophan
- 2,3-Dihydroxybenzoic acid (DHB) used for enterobactin biosynthesis
- The plant hormone salicylic acid
- Many alkaloids and other aromatic metabolites.
- The folate precursor para-aminobenzoate (pABA)
- The biosynthesis of vitamin K and folate in plants and microorganisms.
The name chorismic acid derives from a classical Greek word χωρίζω meaning "to separate", because the compound plays a role as a branch-point in aromatic amino acid biosynthesis.
Biosynthesis
Shikimate → shikimate-3-phosphate → 5-enolpyruvylshikimate-3-phosphate (5-O-(1-carboxyvinyl)-3-phosphoshikimate)
Chorismate synthase is an enzyme that catalyzes the final chemical reaction:
5-O-(1-carboxyvinyl)-3-phosphoshikimate → chorismate + phosphate.
Metabolism
Chorismate is transformed into para-aminobenzoic acid by the enzymes 4-amino-4-deoxychorismate synthase and 4-amino-4-deoxychorismate lyase.
Chorismate lyase is an enzyme that transforms chorismate into 4-hydroxybenzoate and pyruvate. This enzyme catalyses the first step in ubiquinone biosynthesis in Escherichia coli and other Gram-negative bacteria.[citation needed]