- Cis-Dihydroxylation of Tricyclic Arenes and Heteroarenes Catalyzed by Toluene Dioxygenase: A Molecular Docking Study and Experimental Validation
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Molecular docking studies of toluene dioxygenase led to the prediction that angular and lateral cis-dihydroxylation of tricyclic arene and heteroarene substrates could occur. Biotransformations of biphenylene, dibenzofuran, carbazole and dibenzothiophene, using Pseudomonas putida UV4 whole cells, expressing toluene dioxygenase, confirmed that both angular and lateral cis-dihydroxylation had occurred in the predicted regioselective and stereoselective manner. The toluene dioxygenase-catalysed (Pseudomonas putida UV4) biotransformation of dibenzofuran was optimized, to produce 1,2-dihydrodibenzofuran-1,2-diol as the major metabolite in excellent yield. 2-Hydroxydibenzofuran, resulting from dehydration of 1,2-dihydrodibenzofuran-1,2-diol, was also found to undergo cis- dihydroxylation to give a very minor cis-dihydrodiol metabolite. The enantiopurity (>98% ee) and (1R,2S) absolute configuration of the major dibenzofuran cis -dihydrodiol was rigorously established by catalytic hydrogenation and formation of methoxy(trifluoromethyl)phenylacetate derivatives and by X-ray crystallography of an epoxide derivative. Biotransformation of carbazole yielded anthranilic acid as the major metabolite and was consistent with angular cis-dihydroxylation. Synthesis of a cis- diol epoxide derivative showed that the main cis-dihydrodiol metabolite of dibenzofuran has potential in the chemoenzymatic synthesis of natural products. (Figure presented.).
- Boyd, Derek R.,Sharma, Narain D.,Brannigan, Ian N.,McGivern, Christopher J.,Nockemann, Peter,Stevenson, Paul J.,McRoberts, Colin,Hoering, Patrick,Allen, Christopher C. R.
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p. 2526 - 2537
(2019/04/13)
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- Oxygenation reactions of various tricyclic fused aromatic compounds using Escherichia coli and Streptomyces lividans transformants carrying several arene dioxygenase genes.
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Bioconversion (biotransformation) experiments on arenes (aromatic compounds), including various tricyclic fused aromatic compounds such as fluorene, dibenzofuran, dibenzothiophene, carbazole, acridene, and phenanthridine, were done using the cells of Escherichia coli transformants expressing several arene dioxygenase genes. E. coli carrying the phenanthrene dioxygenase (phdABCD) genes derived from the marine bacterium Nocardioides sp. strain KP7 converted all of these tricyclic aromatic compounds, while E. coli carrying the Pseudomonas putida F1 toluene dioxygenase (todC1C2BA) genes or the P. pseudoalcaligenes KF707 biphenyl dioxygenase (bphA1A2A3A4) genes was not able to convert these substrates. Surprisingly, E. coli carrying hybrid dioxygenase (todC1::bphA2A3A4) genes with a subunit substitution between the toluene and biphenyl dioxygenases was able to convert fluorene, dibenzofuran, and dibenzothiophene. The cells of a Streptomyces lividans transformant carrying the phenanthrene dioxygenase genes were also evaluated for bioconversion of various tricyclic fused aromatic compounds. The ability of this actinomycete in their conversion was similar to that of E. coli carrying the corresponding genes. Products converted from the aromatic compounds with these recombinant bacterial cells were purified by column chromatography on silica gel, and identified by their MS and 1H and 13C NMR analyses. Several products, e.g., 4-hydroxyfluorene converted from fluorene, and cis-1,2-dihydroxy-1,2-dihydrophenanthridine, cis-9,10-dihydroxy-9,10-dihydrophenanthridine, and 10-hydroxyphenanthridine, which were converted from phenanthridine, were novel compounds.
- Shindo,Ohnishi,Chun,Takahashi,Hayashi,Saito,Iguchi,Furukawa,Harayama,Horinouchi,Misawa
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p. 2472 - 2481
(2007/10/03)
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- Photochemistry of Dibenzo-1,4-dioxin: Formation of 2,2'-Biphenylquinone as an Observable Intermediate
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Photolysis of dibenzo-1,4-dioxin 1, which is parent ring system of the well-known environmental contaminant 'dioxin' an 2,3,7,8-tetramethyldibenzo-1,4-dioxin 2, in aqueous solution results in an novel intramolecular rearrangement, giving rise to intermedi
- Guan, Bing,Wan, Peter
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p. 409 - 410
(2007/10/02)
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