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Sphingobacterium sp. T2 manganese superoxide dismutase catalyses the oxidative demethylation of polymeric lignin via generation of hydroxyl radical
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Rashid, Goran M. M., Zhang, Xiaoyang, Wilkinson, Rachael C., Fülöp, Vilmos, Cottyn, Betty, Baumberger, Stéphanie and Bugg, Tim (2018) Sphingobacterium sp. T2 manganese superoxide dismutase catalyses the oxidative demethylation of polymeric lignin via generation of hydroxyl radical. ACS Chemical Biology . doi:10.1021/acschembio.8b00557 ISSN 1554-8929.
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WRAP-Sphingobacterium-manganese-superoxide-dismutase-Bugg-2018.pdf - Accepted Version - Requires a PDF viewer. Download (1257Kb) | Preview |
Official URL: http://dx.doi.org/10.1021/acschembio.8b00557
Abstract
Sphingobacterium sp. T2 contains two extracellular manganese superoxide dismutase enzymes which exhibit unprecedented activity for lignin oxidation but via an unknown mechanism. Enzymatic treatment of lignin model compounds gave products whose structures were indicative of aryl–Cα oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. 18O labeling studies on the SpMnSOD-catalyzed oxidation of lignin model compound guiaiacylglycerol-β-guaiacyl ether indicated that the an oxygen atom inserted by the enzyme is derived from superoxide or peroxide. Analysis of an alkali lignin treated by SpMnSOD1 by quantitative 31P NMR spectroscopy demonstrated 20–40% increases in phenolic and aliphatic OH content, consistent with lignin demethylation and some internal oxidative cleavage reactions. Assay for hydroxyl radical generation using a fluorometric hydroxyphenylfluorescein assay revealed the release of 4.1 molar equivalents of hydroxyl radical by SpMnSOD1. Four amino acid replacements in SpMnSOD1 were investigated, and A31H or Y27H site-directed mutant enzymes were found to show no lignin demethylation activity according to 31P NMR analysis. Structure determination of the A31H and Y27H mutant enzymes reveals the repositioning of an N-terminal protein loop, leading to widening of a solvent channel at the dimer interface, which would provide increased solvent access to the Mn center for hydroxyl radical generation.
Item Type: | Journal Article | ||||||||||||
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Subjects: | Q Science > QD Chemistry | ||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry Faculty of Science, Engineering and Medicine > Science > Life Sciences (2010- ) |
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Library of Congress Subject Headings (LCSH): | Aromatic compounds -- Synthesis, Lignin -- Biodegradation, Superoxide dismutase, Hydroxyl group | ||||||||||||
Journal or Publication Title: | ACS Chemical Biology | ||||||||||||
Publisher: | American Chemical Society | ||||||||||||
ISSN: | 1554-8929 | ||||||||||||
Official Date: | 24 September 2018 | ||||||||||||
Dates: |
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DOI: | 10.1021/acschembio.8b00557 | ||||||||||||
Status: | Peer Reviewed | ||||||||||||
Publication Status: | Published | ||||||||||||
Reuse Statement (publisher, data, author rights): | “This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Chemical Biology, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see Articles on Request author-directed link to Published Work, see http://pubs.acs.org/page/policy/articlesonrequest/index.html].” | ||||||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||||||
Date of first compliant deposit: | 16 October 2018 | ||||||||||||
Date of first compliant Open Access: | 24 September 2019 | ||||||||||||
RIOXX Funder/Project Grant: |
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