Sphingobacterium sp T2 manganese superoxide dismutase catalyzes the oxidative demethylation of polymeric lignin via generation of hydroxyl radical - INRAE - Institut national de recherche pour l’agriculture, l’alimentation et l’environnement Accéder directement au contenu
Article Dans Une Revue ACS Chemical Biology Année : 2018

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

Résumé

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 alpha oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. O-18 labeling studies on the SpMnSOD-catalyzed oxidation of lignin model compound guiaiacylglycerol-beta-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-31 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-31 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.
Fichier principal
Vignette du fichier
ACS Chem Biol 2018.pdf (3.58 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-02622195 , version 1 (04-03-2024)

Identifiants

Citer

Goran M. M. Rashid, Xiaoyang Zhang, Rachael C. Wilkinson, Vilmos Fülöp, Betty Cottyn Boitte, et al.. Sphingobacterium sp T2 manganese superoxide dismutase catalyzes the oxidative demethylation of polymeric lignin via generation of hydroxyl radical. ACS Chemical Biology, 2018, 13 (10), pp.2920-2929. ⟨10.1021/acschembio.8b00557⟩. ⟨hal-02622195⟩
47 Consultations
6 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More