Synthetic xylan-binding modules for mapping of pulp fibres and wood sections

A panel of synthetic xylan-binding CBMs, previously selected from a molecular library based on the scaffold of CBM4-2 from xylanase Xyn10A of Rhodothermus marinus, was used in this study. The wild type CBM4-2 and evolved modules both showed binding to wood sections. However, differences were observed in the staining patterns suggesting that these modules have different xylan-binding properties. Also the staining stability varied between the CBMs, the most stable staining being obtained with one (X-2) of the synthetic modules. Treatment of wood materials resulted in altered signal intensities, thereby also demonstrating the potential application of engineered CBMs as analytical tools for quality assessment of diverse plant material processes.In this study we have demonstrated the usefulness of synthetic xylan-binding modules as specific probes in analysis of hemicelluloses (xylan) in wood and fibre materials.Wood cell walls represent highly complex biocomposites that consists of repertoires of polysaccharides and lignins integrated into a three-dimensional conglomerate [1,2]. At the microstructural level, wood cell walls are composed of both primary- and dominating secondary cell wall layers in which the major (cellulose, lignin and hemicelluloses) and minor (pectins, proteins) chemical components are heterogeneously dispersed and integrated. Understanding the cell wall's complexity is of great interest both for plant biology and for plant processing in food and pulp industry.One of the key main challenges for an improved understanding of wood cell wall structure especially, in relation to properties, is an ability to specifically localise and visualised the spatial distribution of the major polysaccharide components (cellulose and hemicelluloses) in vivo. In lignified cell walls this is quite challenging since the hemicelluloses interface between the cellulose and lignin forming a heterogeneous polymer complex and it is exacting to distinguish between the various co