Cellulase-lignin interactions: The role of carbohydrate-binding module and pH in non-productive binding

Jenni Rahikainen, James David Evans, Saara Mikander, Anna Kalliola, T. Puranen, Tarja Tamminen, Kaisa Marjamaa, Kristiina Kruus (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

97 Citations (Scopus)

Abstract

Non-productive cellulase adsorption onto lignin is a major inhibitory mechanism preventing enzymatic hydrolysis of lignocellulosic feedstocks. Therefore, understanding of enzyme–lignin interactions is essential for the development of enzyme mixtures and processes for lignocellulose hydrolysis. We have studied cellulase–lignin interactions using model enzymes, Melanocarpus albomyces Cel45A endoglucanase (MaCel45A) and its fusions with native and mutated carbohydrate-binding modules (CBMs) from Trichoderma reesei Cel7A. Binding of MaCel45A to lignin was dependent on pH in the presence and absence of the CBM; at high pH, less enzyme bound to isolated lignins. Potentiometric titration of the lignin preparations showed that negatively charged groups were present in the lignin samples and that negative charge in the samples was increased with increasing pH. The results suggest that electrostatic interactions contributed to non-productive enzyme adsorption: Reduced enzyme binding at high pH was presumably due to repulsive electrostatic interactions between the enzymes and lignin. The CBM increased binding of MaCel45A to the isolated lignins only at high pH. Hydrophobic interactions are probably involved in CBM binding to lignin, because the same aromatic amino acids that are essential in CBM–cellulose interaction were also shown to contribute to lignin-binding.
Original languageEnglish
Pages (from-to)315-321
Number of pages6
JournalEnzyme and Microbial Technology
Volume53
Issue number5
DOIs
Publication statusPublished - 2013
MoE publication typeA1 Journal article-refereed

Keywords

  • CBM
  • cellulase
  • electrostatic interaction
  • ligning
  • lignocellulose
  • non-productive binding

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