6GSB

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

6GSB の概要

• エントリーDOI: 10.2210/pdb6gsb/pdb
• 分子名称: Superoxide dismutase, MANGANESE (II) ION (3 entities in total)
• 機能のキーワード: oxidoreductase, lignin valorisation, lignin oxidation, manganese keywds 2 superoxide dismutase, sphingobacterium
• 由来する生物種: Sphingobacterium spiritivorum
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 46001.17

構造登録者

Rashid, G.M.,Zhang, X.,Wilkinson, R.C.,Fulop, V.,Cottyn, B.,Baumberger, S.,Bugg, D.H. (登録日: 2018-06-13, 公開日: 2018-10-03, 最終更新日: 2024-01-17)

主引用文献

Rashid, G.M.M.,Zhang, X.,Wilkinson, R.C.,Fulop, V.,Cottyn, B.,Baumberger, S.,Bugg, T.D.H.
Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical.
ACS Chem. Biol., 13:2920-2929, 2018

PubMed 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. O 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 P 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 P 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.

PubMed: 30247873
DOI: 10.1021/acschembio.8b00557

実験手法

X-RAY DIFFRACTION (1.45 Å)