Enzymatic degradation of lignin‐carbohydrate complexes (LCCs): Model studies using a fungal glucuronoyl esterase from Cerrena unicolor

Clotilde d'Errico, Jonas O. Jørgensen, Kristian B. R. M. Krogh, Nikolaj Spodsberg, Robert Madsen, Rune Nygaard Monrad

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Lignin‐carbohydrate complexes (LCCs) are believed to influence the recalcitrance of lignocellulosic plant material preventing optimal utilization of biomass in e.g. forestry, feed and biofuel applications. The recently emerged carbohydrate esterase (CE) 15 family of glucuronoyl esterases (GEs) has been proposed to degrade ester LCC bonds between glucuronic acids in xylans and lignin alcohols thereby potentially improving delignification of lignocellulosic biomass when applied in conjunction with other cellulases, hemicellulases and oxidoreductases. Herein, we report the synthesis of four new GE model substrates comprising α‐ and ɣ‐arylalkyl esters representative of the lignin part of naturally occurring ester LCCs as well as the cloning and purification of a novel GE from Cerrena unicolor (CuGE). Together with a known GE from Schizophyllum commune (ScGE), CuGE was biochemically characterized by means of Michaelis–Menten kinetics with respect to substrate specificity using the synthesized compounds. For both enzymes, a strong preference for 4‐O‐methyl glucuronoyl esters rather than unsubstituted glucuronoyl esters was observed. Moreover, we found that α‐arylalkyl esters of methyl α‐D‐glucuronic acid are more easily cleaved by GEs than their corresponding ɣ‐arylalkyl esters. Furthermore, our results suggest a preference of CuGE for glucuronoyl esters of bulky alcohols supporting the suggested biological action of GEs on LCCs. The synthesis of relevant GE model substrates presented here may provide a valuable tool for the screening, selection and development of industrially relevant GEs for delignification of biomass. Biotechnol. Bioeng. 2015;112: 914–922. © 2014 Wiley Periodicals, Inc.
Original languageEnglish
JournalBiotechnology and Bioengineering
Volume112
Issue number5
Pages (from-to)914-922
Number of pages9
ISSN0006-3592
DOIs
Publication statusPublished - 2015

Keywords

  • Enzymatic delignification
  • Lignin‐carbohydrate complexes
  • Glucuronoyl esterase
  • Cerrena unicolor
  • Schizophyllum commune
  • Substrate specificity

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