404875-12-3Relevant articles and documents
Cis-Dihydroxylation of Tricyclic Arenes and Heteroarenes Catalyzed by Toluene Dioxygenase: A Molecular Docking Study and Experimental Validation
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.
, p. 2526 - 2537 (2019/04/13)
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.).
Retuning rieske-type oxygenases to expand substrate range
Mohammadi, Mahmood,Viger, Jean-Francois,Kumar, Pravindra,Barriault, Diane,Bolin, Jeffrey T.,Sylvestre, Michel
experimental part, p. 27612 - 27621 (2012/03/27)
Rieske-type oxygenases are promising biocatalysts for the destruction of persistent pollutants or for the synthesis of fine chemicals. In this work, we explored pathways through which Rieske-type oxygenases evolve to expand their substrate range. BphAEp4, a variant biphenyl dioxygenase generated from Burkholderia xenovorans LB400 BphAELB400 by the double substitution T335A/F336M, and BphAERR41, obtained by changing Asn338, Ile341, and Leu409 of BphAE p4 to Gln338, Val341, and Phe409, metabolize dibenzofuran two and three times faster than BphAELB400, respectively. Steady-state kinetic measurements of single- and multiple-substitution mutants of BphAELB400 showed that the single T335A and the double N338Q/L409F substitutions contribute significantly to enhanced catalytic activity toward dibenzofuran. Analysis of crystal structures showed that the T335A substitution relieves constraints on a segment lining the catalytic cavity, allowing a significant displacement in response to dibenzofuran binding. The combined N338Q/L409F substitutions alter substrate-induced conformational changes of protein groups involved in subunit assembly and in the chemical steps of the reaction. This suggests a responsive induced fit mechanism that retunes the alignment of protein atoms involved in the chemical steps of the reaction. These enzymes can thus expand their substrate range through mutations that alter the constraints or plasticity of the catalytic cavity to accommodate new substrates or that alter the induced fit mechanism required to achieve proper alignment of reactioncritical atoms or groups.
