Polyphenol Oxidase Activity on Guaiacyl and Syringyl Lignin Units.

Autor: de O G Silva C; Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, Kgs., Lyngby, 2800, Denmark., Sun P; Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The, Netherlands., Barrett K; Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, Kgs., Lyngby, 2800, Denmark., Sanders MG; Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The, Netherlands., van Berkel WJH; Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The, Netherlands., Kabel MA; Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG, Wageningen, The, Netherlands., Meyer AS; Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, Kgs., Lyngby, 2800, Denmark., Agger JW; Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, Kgs., Lyngby, 2800, Denmark.
Jazyk: angličtina
Zdroj: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2024 Nov 25; Vol. 63 (48), pp. e202409324. Date of Electronic Publication: 2024 Oct 30.
DOI: 10.1002/anie.202409324
Abstrakt: The natural heterogeneity of guaiacyl (G) and syringyl (S) compounds resulting from lignin processing hampers their direct use as plant-based chemicals and materials. Herein, we explore six short polyphenol oxidases (PPOs) from lignocellulose-degrading ascomycetes for their capacity to react with G-type and S-type phenolic compounds. All six PPOs catalyze the ortho-hydroxylation of G-type compounds (guaiacol, vanillic acid, and ferulic acid), forming the corresponding methoxy-ortho-diphenols. Remarkably, a subset of these PPOs is also active towards S-compounds (syringol, syringic acid, and sinapic acid) resulting in identical methoxy-ortho-diphenols. Assays with 18 O 2 demonstrate that these PPOs in particular catalyze ortho-hydroxylation and ortho-demethoxylation of S-compounds and generate methanol as a co-product. Oxidative (ortho-) demethoxylation of S-compounds is a novel reaction for PPOs, which we propose occurs by a distinct reaction mechanism as compared to aryl-O-demethylases. We further show that addition of a reducing agent can steer the PPO reaction to form methoxy-ortho-diphenols from both G- and S-type substrates rather than reactive quinones that lead to unfavorable polymerization. Application of PPOs opens for new routes to reduce the heterogeneity and methoxylation degree of mixtures of G and S lignin-derived compounds.
(© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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