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Appl. Environ. Microbiol., 04 1996, 1364-1368, Vol 62, No. 4
SM Resnick and DT Gibson
Bacterial strains expressing naphthalene, biphenyl, and toluene dioxygenase
were examined for their abilities to oxidize 6,7-dihydro-5H-
benzocycloheptene (benzocyclohept-1-ene). The major oxidation products were
isolated, and their absolute configurations were determined by chiral 1H
nuclear magnetic resonance analysis of diastereomeric boronate esters,
chiral stationary-phase high-pressure liquid chromatography, and
stereo-chemical correlation. Pseudomonas sp. strain 9816/11 and
Sphingomonas yanoikuyae (formerly identified as a Beijerinckia sp.) B8/36
expressing naphthalene and biphenyl dioxygenases, respectively, oxidized
benzocyclohept-1-ene to a major product identified as
(-)-(1R,2S)-cis-dihydroxybenzocycloheptane (> 98% enantiomeric excess
[ee], 50 and 90% yield, respectively). In contrast, Pseudomonas putida
F39/D expressing toluene dioxygenase oxidized benzocyclohept-1-ene to
(+)-(5R)-hydroxybenzocyclohept-1-ene (> 98% ee, 90% yield) as the major
metabolite and to the "opposite" diol, (+)-
(1S,2R)-cis-dihydroxybenzocycloheptane (> 98% ee, 10% yield). The
results indicate that, for benzocyclohept-1-ene, the major reaction
catalyzed by naphthalene and biphenyl dioxygenases is dioxygenation whereas
toluene dioxygenase catalyzes mainly R-stereospecific benzylic
monooxygenation. Although the type of reaction catalyzed by each organism
was not predictable, the absolute configuration of the diol and monol
products formed by naphthalene and toluene dioxygenases are consistent with
the stereochemistry of the products formed by these enzymes from other
benzocycloalkene substrates.
Copyright © 1996, American Society for Microbiology
Oxidation of 6,7-dihydro-5H-benzocycloheptene by bacterial strains expressing naphthalene dioxygenase, biphenyl dioxygenase, and toluene dioxygenase yields homochiral monol or cis-diol enantiomers as major products
Department of Microbiology, University of Iowa, Iowa City 52242, USA. sresink@vaxa.weeg.uiowa.edu
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