Isochorismic acid, also called isochorismate, is an organic

dibasic acid An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

synthesized from

chorismate 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 d ...

Synthesis

The enzyme chorismate hydroxymutase (isochorismate synthase, CF 5.4.4.2) reversibly isomerizes chorismate into isochorismate, giving rise to one of the branches of the

shikimate Shikimic acid, more commonly known as its anionic form shikimate, is a cyclohexene, a cyclitol and a cyclohexanecarboxylic acid. It is an important biochemical metabolite in plants and microorganisms. Its name comes from the Japanese flower ''shik ...

pathway. Isochorismate is a precursor in the biosynthesis of many natural compounds. Salicylic acid and terpenoid naphthoquinones (menaquinones, phylloquinones) are synthesized from isochorismate, although in some organisms these compounds can be synthesized from chorismate in alternative ways, not through isochorismate (for example, the futalosine pathway of menaquinone biosynthesis in some prokaryotes).

Discovery

The compound was discovered by Australian researchers in 1968 as an intermediate in the biosynthesis of 2,3-dihydroxybenzoate (ortho-pyrocatechate, an

enterobactin Enterobactin (also known as enterochelin) is a high affinity siderophore that acquires iron for microbial systems. It is primarily found in Gram-negative bacteria, such as ''Escherichia coli'' and ''Salmonella typhimurium''. Enterobactin is the s ...

precursor) from chorismate in '' Aerobacter aerogenes''. The reaction presumably proceeds via nucleophilic attack of water at the carbon atom. The trivial name "isochorismic acid", which has been fixed for the compound, was proposed by these researchers, who described the substance for the first time.

Properties

Isochorismic acid is a thermodynamically unstable compound. In an aqueous solution at room temperature and pH = 7, isochorismate decomposes into a mixture of salicylate and meta-carboxyphenylpyruvate.{{cite book , last1=Haslam , first1=Edwin , title=The Shikimate Pathway: Biosynthesis of Natural Products Series , date=20 May 2014 , publisher=

Elsevier Elsevier ( ) is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell (journal), Cell'', the ScienceDirect collection of electronic journals, ...

, isbn=978-1-4831-6118-1 , page=98 , url=https://books.google.com/books?id=FqyQBQAAQBAJ&dq=Isochorismic+acid&pg=PA98 , access-date=13 June 2025 , language=en The latter is formed from isoprephenate (also a thermodynamically unstable compound), which arises as a result of the ,3sigmatropic rearrangement of isochorismate.

References

Dicarboxylic acids Hydroxy acids Benzoic acids Enoic acids