Cellulose and xylan are the two most abundant polysaccharides in plant biomass. Together, they form the cell walls in materials such as wood and straw. While cellulose is widely used for the production of sustainable and eco-friendly materials, xylan has only recently begun to be explored for the same purposes. The heterogeneity of natural xylan polysaccharides complicates investigations into the molecular basis of xylan-cellulose interactions, which determine strength and digestibility of the cell wall, and are thus key to the development of improved methods for biomass exploitation.<br/><br/>Well-defined molecular tools mimicking natural xylan polysaccharides have great potential for studying structure and properties of xylan, including its interaction with cellulose. We present here the chemoenzymatic synthesis of a series of xylan polysaccharides with perfectly regular patterns of arabinose substitution. Our approach is based on the chemical synthesis of arabinoxylan oligosaccharide building blocks that are subsequently polymerized using a xylan glycosynthase enzyme. The obtained polysaccharides contain polysaccharide chains with molecular masses up to 80 kDa (606 monosaccharides). Due to the defined nature of the polysaccharide substitution patterns, specific properties were observed for particular members of the prepared arabinoxylan collection rather than the simple linear correlation between e.g. crystallinity and degree of substitution reported previously for arabinoxylans obtained from natural sources.

Chemoenzymatic synthesis of artificial xylan polysaccharides with defined substitution patterns

2019 Spring National Meeting

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