title: Effects of Xylan Side-Chain Substitutions on Xylan-Cellulose Interactions and Implications for Thermal Pretreatment of Cellulosic Biomass.
abstract: Lignocellulosic biomass is mainly constituted by cellulose, hemicellulose, and lignin and represents an important resource for the sustainable production of biofuels and green chemistry materials. Xylans, a common hemicellulose, interact with cellulose and often exhibit various side chain substitutions including acetate, (4-O-methyl) glucuronic acid, and arabinose. Recent studies have shown that the distribution of xylan substitutions is not random, but follows patterns that are dependent on the plant taxonomic family and cell wall type. Here, we use molecular dynamics simulations to investigate the role of substitutions on xylan interactions with the hydrophilic cellulose face, using the recently discovered xylan decoration pattern of the conifer gymnosperms as a model. The results show that α-1,2-linked substitutions stabilize the binding of single xylan chains independently of the nature of the substitution and that Ca2+ions can mediate cross-links between glucuronic acid substitutions of two neighboring xylan chains, thus stabilizing binding. At high temperature, xylans move from the hydrophilic to the hydrophobic cellulose surface and are also stabilized by Ca2+cross-links. Our results help to explain the role of substitutions on xylan-cellulose interactions, and improve our understanding of the plant cell wall architecture and the fundamentals of biomass pretreatments.
authors.affiliation: Institute of Chemistry, University of Campinas , Campinas, Sao Paulo 13084-862, Brazil.
authors.forename: Caroline S
authors.initials: CS
authors.lastname: Pereira
authors.affiliation: Institute of Chemistry, University of Campinas , Campinas, Sao Paulo 13084-862, Brazil.
authors.forename: Rodrigo L
authors.initials: RL
authors.lastname: Silveira
authors.affiliation: Department of Biochemistry and the Leverhulme Natural Material Innovation Centre, University of Cambridge , Tennis Court Road, Cambridge, CB2 1QW, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.affiliation: Institute of Chemistry, University of Campinas , Campinas, Sao Paulo 13084-862, Brazil.
authors.forename: Munir S
authors.identifier: 0000-0001-7485-1228
authors.initials: MS
authors.lastname: Skaf
mesh_terms: D000085:Acetates / Q000737:chemistry*; D001089:Arabinose / Q000737:chemistry*; D018533:Biomass; D002118:Calcium / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry*; D006358:Hot Temperature; D057927:Hydrophobic and Hydrophilic Interactions; D020894:Microfibrils / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D013499:Surface Properties; D014990:Xylans / Q000737:chemistry*
chemical_list: D000085:Acetates; D003432:Cross-Linking Reagents; D014990:Xylans; D020723:Glucuronic Acid; D002482:Cellulose; D001089:Arabinose; D002118:Calcium