bm7b00067_si_001.pdf (2.6 MB)
Effects of Xylan Side-Chain Substitutions on Xylan–Cellulose Interactions and Implications for Thermal Pretreatment of Cellulosic Biomass
journal contribution
posted on 2017-03-02, 00:00 authored by Caroline
S. Pereira, Rodrigo L. Silveira, Paul Dupree, Munir S. SkafLignocellulosic 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.