BerAbbreviations CI: compound I (of peroxidase catalytic cycle); CII: compound II (of peroxidase catalytic cycle); DHP: dehydrogenation polymer (in vitro synthesized lignin); DTT: dithiothreitol; EDTA: ethylenediaminetetraacetic acid; G: guaiacyl (lignin unit); HSQC: heteronuclear singlequantum correlation; k2 and k3: firstorder price constants for CI and CII reduction, respectively; k2app and k3app: apparent secondorder rate constants for CI and CII reduction, respectively; KD2 and KD3: equilibrium dissociation constants for CI and CII reduction, respectively; kobs: pseudofirstorder rate continual; LiP: lignin peroxidase; LRET: longrange electron transfer; Mp: main peak (in SEC); NMR: nuclear magnetic resonance; 2-Oxosuccinic acid Endogenous Metabolite PyGCMS: pyrolysisgas chromatographymass spectrometry; S: syringyl (lignin unit); SEC: sizeexclusion chromatography; VP: versatile peroxidase. Authors’ contributions VSJ and FJRD performed the majority of the biochemical experimental perform and data evaluation. JR performed the NMR study and sample derivatization. MARC con tributed optimization of lignosulfonate methylation. AG contributed chemical analyses. All authors contributed towards the discussion of outcomes, and critically revised the manuscript. VSJ and ATM wrote the paper. All authors study and authorized the final manuscript. Author information 1 CSIC, Centro de Investigaciones Biol icas, Ramiro de Maeztu 9, 28040 Madrid, Spain. two Division of Biology and Biological Engineering, Chalmers University of Technologies, 41296 Gothenburg, Sweden. 3 CSIC, Instituto de Recursos Naturales y Agrobiolog de Sevilla, Avenida Reina Mer cedes ten, 41012 Seville, Spain. 4 Department of Organic Chemistry, University of Seville, Prof. Garc Gonz ez sn, 41012 Seville, Spain. Acknowledgements We thank Dr. Guro E. Fredheim (Borregaard AS, Sarpsborg, Norway) for provid ing the lignosulfonate preparations, and Dr. Manuel Angulo (CITIUS, University of Seville) for performing the NMR analyses. We acknowledge support in the publication fee by the CSIC Open Access Publication Help Initiative through its Unit of Info Resources for Analysis (URICI). Competing interests The authors declare that they have no competing interests. Funding This work was supported by the INDOX (KBBE2013613549 to ATM) and EnzOx2 (H2020BBIPPP2015RIA720297 to ATM) EU projects, and also the NOESIS (BIO201456388R to FJRD), BIORENZYMERY (AGL201453730R to AG) and LIGNIN (CTQ201460764JIN to JR) projects with the Spanish Ministry of Economy and Competitiveness (MINECO) cofinanced by FEDER funds.References 1. Mart ez AT, RuizDue s FJ, Mart ez MJ, del R JC, Guti rez A. Enzy matic delignification of plant cell wall: from nature to mill. Curr Opin Biotechnol. 2009;20:3487. 2. Bozell JJ, Petersen GR. Technology development for the production of biobased products from biorefinery carbohydratesthe US Division of Energy’s “Top 10” revisited. Green Chem. 2010;12:5394. three. Ragauskas AJ, Beckham GT, Biddy MJ, Chandra R, Chen F, Davis MF, Davison BH, Dixon RA, Gilna P, Keller M, Langan P, Naskar AK, Saddler JN, Tschaplinski T, Tuskan GA, Wyman CE. Lignin valorization: enhancing lignin processing inside the biorefinery. Science. 2014;344:1246843. 4. Pandey A, Hofer R, Larroche C, Taherzadeh M, Nampoothiri M. Industrial biorefineries and white biotechnology. Amsterdam: Elsevier; 2015. five. Shahid M, Mohammad F, Chen G, Tang RC, Xing T. Enzymatic method ing of organic fibres: white biotechnology for sustainable development. Green Chem. 2016;18:22561. six. Mart ez AT, Spe.