Regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene by naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4

Appl Environ Microbiol. 1996 Nov;62(11):4073-80. doi: 10.1128/aem.62.11.4073-4080.1996.


The regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene was examined with mutant and recombinant strains expressing naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4. The initial oxidation products were isolated and identified by gas chromatography-mass spectrometry and nuclear magnetic resonance spectrometry. Salicylate-induced cells of Pseudomonas sp. strain 9816/11 and isopropyl-beta-D-thiogalactopyranoside-induced cells of Escherichia coli JM109(DE3)(pDTG141) oxidized fluorene to (+)-(3S,4R)-cis-3,4-dihydroxy-3,4-dihydrofluorene (80 to 90% relative yield; > 95% enantiomeric excess [ee]) and 9-fluorenol (< 10% yield). The same cells oxidized dibenzofuran to (1R,2S)-cis-1,2-dihydroxy-1, 2-dihydrodibenzofuran (60 to 70% yield; > 95% ee) and (3S,4R)-cis-3, 4-dihydroxy-3,4-dihydrodibenzofuran (30 to 40% yield; > 95% ee). Induced cells of both strains, as well as the purified dioxygenase, also oxidized dibenzothiophene to (+)-(1R,2S)-cis-1,2-dihydroxy-1, 2-dihydrodibenzothiophene (84 to 87% yield; > 95% ee) and dibenzothiophene sulfoxide (< 15% yield). The major reaction catalyzed by naphthalene dioxygenase with each substrate was stereospecific dihydroxylation in which the cis-dihydrodiols were of identical regiochemistry and of R configuration at the benzylic center adjacent to the bridgehead carbon atom. The regiospecific oxidation of dibenzofuran differed from that of the other substrates in that a significant amount of the minor cis-3,4-dihydrodiol regioisomer was formed. The results indicate that although the absolute stereochemistry of the cis-diene diols was the same, the nature of the bridging atom or heteroatom influenced the regiospecificity of the reactions catalyzed by naphthalene dioxygenase.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Benzofurans / chemistry
  • Benzofurans / metabolism
  • Biotransformation
  • Dioxygenases
  • Escherichia coli / genetics
  • Fluorenes / chemistry
  • Fluorenes / metabolism
  • Magnetic Resonance Spectroscopy
  • Multienzyme Complexes / genetics
  • Multienzyme Complexes / metabolism*
  • Mutation
  • Oxidation-Reduction
  • Oxygenases / genetics
  • Oxygenases / metabolism*
  • Pseudomonas / enzymology*
  • Pseudomonas / genetics
  • Recombination, Genetic
  • Stereoisomerism
  • Substrate Specificity
  • Thiophenes / chemistry
  • Thiophenes / metabolism


  • Benzofurans
  • Fluorenes
  • Multienzyme Complexes
  • Thiophenes
  • fluorene
  • dibenzofuran
  • Oxygenases
  • Dioxygenases
  • naphthalene dioxygenase
  • dibenzothiophene