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Appl. Environ. Microbiol., 11 1996, 4073-4080, Vol 62, No. 11
SM Resnick and DT Gibson
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.
Copyright © 1996, American Society for Microbiology
Regio- and stereospecific oxidation of fluorene, dibenzofuran, and dibenzothiophene by naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4
Department of Microbiology, University of Iowa, Iowa City 52242, USA. sol-resnick@uiowa.edu
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