Toluene and ethylbenzene oxidation by purified naphthalene dioxygenase from Pseudomonas sp. strain NCIB 9816-4.
Purified naphthalene dioxygenase (NDO) from Pseudomonas sp. strain NCIB 9816-4 oxidized toluene to benzyl alcohol and benzaldehyde by reactions involving benzylic monooxygenation and dioxygen-dependent alcohol oxidation, respectively. Xylene and nitrotoluene isomers were also oxidized to substituted benzyl alcohol and benzaldehyde derivatives. NDO oxidized ethylbenzene sequentially through (S)-1-phenethyl alcohol (77% enantiomeric excess) and acetophenone to 2-hydroxyacetophenone. In addition, NDO also oxidized ethylbenzene through styrene to (R)-1-phenyl-1,2-ethanediol (74% enantiomeric excess) by reactions involving desaturation and dihydroxylation, respectively. Isotope experiments with 18O2, H2 18O, and D2O suggest that 1-phenethyl alcohol is oxidized to acetophenone by a minor reaction involving desaturation followed by tautomerization. The major reaction in the conversion of 1-phenethyl alcohol and benzyl alcohol to acetophenone and benzaldehyde, respectively, probably involves monohydroxylation to form a gem-diol intermediate which stereospecifically loses the incoming hydroxyl group to leave the carbonyl product. These results are compared with similar reactions catalyzed by cytochrome P-450.
Lee
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Department of Microbiology, University of Iowa, Iowa City 52242, USA.
Gibson
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DT
D001555:Benzene Derivatives / Q000378:metabolism*; D049308:Dioxygenases; D009097:Multienzyme Complexes / Q000494:pharmacology*; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000494:pharmacology*; D011549:Pseudomonas / Q000201:enzymology*; D014050:Toluene / Q000378:metabolism*
D001555:Benzene Derivatives; D009097:Multienzyme Complexes; D014050:Toluene; D010105:Oxygenases; D049308:Dioxygenases; C038703:naphthalene dioxygenase; C004912:ethylbenzene