Xylan represents the main hemicellulose component in the secondary plant cell walls of flowering plants. Xylan is a polysaccharide made from units of xylose and contains predominantly β-D-xylose units linked as in cellulose.
Two different Xylan fractions are extracted from spruce wood using an alkaline process (AGX-A) and a hydrothermal process by subcritical water (AGX-H). AGX-A shows lower relative glucuronation and higher arabinosylation compare with AGX-H. These differences in substitution may arise from the different extractability of distinct Xylan populations in softwoods or be induced by the extraction process. mGlcA substitutions do not affect significantly the conformational space of the Xylan backbone, neither in their protonated nor deprotonated state[1].
[1]. Martinez-Abad A, et al. Regular Motifs in Xylan Modulate Molecular Flexibility and Interactions with Cellulose Surfaces. Plant Physiol. 2017 Oct 25. pii: pp.01184.2017.