6gsb | pdb_00006gsb

Sphingobacterium sp. T2 manganese superoxide dismutase catalyses the oxidative demethylation of polymeric lignin via generation of hydroxyl radical

spinqualitylabelsall models 6gsb, resolution 1.45Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6gsb is a 2 chain structure with sequence from Atcc 33861. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: MN Activity: Superoxide dismutase, with EC number 1.15.1.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [A0A0M3KL50_9SPHI] Destroys radicals which are normally produced within the cells and which are toxic to biological systems.[RuleBase:RU000414] Publication Abstract from PubMed 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-C oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. 18O labelling studies on the SpMnSOD-catalysed oxidation of lignin model compound guiaiacylglycerol--guaiacyl ether indicated that the 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 approximately 1 molar equivalent 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 centre for hydroxyl radical generation. Sphingobacterium sp. T2 manganese superoxide dismutase catalyses the oxidative demethylation of polymeric lignin via generation of hydroxyl radical.,Rashid GMM, Zhang X, Wilkinson RC, Fulop V, Cottyn B, Baumberger S, Bugg TDH ACS Chem Biol. 2018 Sep 24. doi: 10.1021/acschembio.8b00557. PMID:30247873 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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