Sequential oxygenation of linoleic acid in the fungus Gaeumannomyces graminis: stereochemistry of dioxygenase and hydroperoxide isomerase reactions

Arch Biochem Biophys. 1994 Feb 15;309(1):77-80. doi: 10.1006/abbi.1994.1087.


Linoleic acid is sequentially oxygenated to (7S,8S)-dihydroxylinoleic acid by dioxygenase and hydroperoxide isomerase activities present in the fungus Gaeumannomyces graminis (Brodowsky, I. D., Hamberg, M., and Oliw, E. H., J. Biol. Chem. 267, 14738-14745 (1992)). Linoleic acids stereospecifically deuterated at C-7 and C-8 were prepared by biological desaturation of the corresponding stearates and used to determine the stereochemistry of the hydrogen abstractions occurring in the dioxygenase- and hydroperoxide isomerase-catalyzed reactions. The dioxygenase reaction was found to involve stereospecific abstraction of the pro-S hydrogen from C-8 followed by antarafacial insertion of dioxygen to produce (8R)-hydroperoxylinoleic acid. The hydroperoxide isomerase reaction consisted of conversion of (8R)-hydroperoxylinoleic acid into (7S,8S)-dihydroxylinoleic acid by stereospecific elimination of the pro-S hydrogen from C-7 and intramolecular suprafacial insertion of oxygen at C-7. Accordingly, during the conversion of linoleic acid into (8R)-hydroperoxylinoleic acid, the absolute configuration of C-8 was inverted, while the conversion of (8R)-hydroperoxylinoleic acid into (7S,8S)-dihydroxylinoleic acid occurred with retention of absolute configuration at C-7.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Deuterium
  • Intramolecular Oxidoreductases*
  • Isomerases / metabolism*
  • Linoleic Acid
  • Linoleic Acids / chemistry
  • Linoleic Acids / metabolism*
  • Molecular Conformation
  • Oxidation-Reduction
  • Xylariales / enzymology*


  • Linoleic Acids
  • Linoleic Acid
  • Deuterium
  • Isomerases
  • Intramolecular Oxidoreductases
  • hydroperoxide isomerase