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Synthesis of substituted catechols using nitroarene dioxygenases

Paper ID Volume ID Publish Year Pages File Format Full-Text
18571 42726 2006 6 PDF Available
Title
Synthesis of substituted catechols using nitroarene dioxygenases
Abstract

The nitroarene dioxygenases are in the class of Rieske iron-containing oxygenases that incorporate atmospheric oxygen into substrates via electrophilic attack on the substrate. In their native role, the nitroarene dioxygenases start degradative pathways by hydroxylating nitro-substituted, and adjacent unsubstituted carbons of nitroaromatic compounds. The reaction yields the corresponding nitro-cis-cyclohexadienediol, which is unstable and spontaneously re-aromatizes to form a catechol and nitrite. In bacterial metabolism, the specificity of the hydroxylation determines subsequent steps in degradation pathways. Experiments were done to find whether the specificity could be exploited to direct the hydroxylation of multiply substituted aromatic substrates and thereby produce novel catechols. Recombinant strains carrying genes for nitroarene dioxygenases were used for transformation of various substituted nitroaromatic compounds. The reactions were analyzed using HPLC to track substrate consumption and product formation, then GC–MS and NMR to identify the reaction products. A number of substituted catechols were obtained using the recombinant biocatalysts. The nitro-substituted carbon was the primary site for dioxygenase hydroxylation. When substrates included nitro and halogen substituents, the halogen-substituted positions were also targeted, but less frequently than the nitro-substituted site. The production of catechols was limited in batch fermentations, likely due to toxicity of the quinones that result from air oxidation of catechols. The nitroarene dioxygenases will serve as catalysts for direct synthesis of highly substituted catechols, however, the reaction conditions must be engineered to overcome product toxicity and allow sustained accumulation of catecholic products.

Keywords
Biocatalysis; Dioxygenase; Catechol; Whole-cell biotransformations
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Synthesis of substituted catechols using nitroarene dioxygenases
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 38, Issues 1–2, 3 January 2006, Pages 142–147
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us