Isolation and identification of the reaction product of alpha-hydroxy-gamma-carboxymuconic epsilon-semialdehyde dehydrogenase

J Biochem. 1979 Dec;86(6):1671-7. doi: 10.1093/oxfordjournals.jbchem.a132687.


The reaction product of enzymic dehydrogenation of alpha-hydroxy-gamma-carboxymuconic epsilon-semialdehyde (HCMS) was isolated. The analytical data (elemental analyses, IR spectra, mass spectra, proton NMR spectra, and UV spectra) showed that the product was not alpha-hydroxy-gamma-carboxymuconic acid (HCMA), the expected primary product of HCMS dehydrogenation, but a lactone of HCMA. The structure of the lactone was tentatively determined as alpha-pyrone-4,6-dicarboxylic acid. HCMS was converted stoichiometrically to the lactone by the purified NAD(P)-linked HCMS dehydrogenase. The lactone was actively metabolized by a cell-free extract prepared from Pseudomonas ochraceae grown on phthalic acid, suggesting that it may be a metabolic intermediate in the bacterial metabolism of protocatechuic acid. Furthermore, a method for the chemical synthesis of the lactose of HCMA is presented and some of its chemical and biochemical properties are described.

MeSH terms

  • Aldehyde Oxidoreductases / metabolism*
  • Aldehydes
  • Dicarboxylic Acids
  • Magnetic Resonance Spectroscopy
  • Mass Spectrometry
  • Pseudomonas / enzymology*
  • Pyrans / isolation & purification*
  • Pyrones / isolation & purification*
  • Spectrophotometry, Infrared
  • Spectrophotometry, Ultraviolet


  • Aldehydes
  • Dicarboxylic Acids
  • Pyrans
  • Pyrones
  • Aldehyde Oxidoreductases