Enzymatic oxidation of plant polysaccharides adsorbed to cellulose surfaces

The development of renewable energy and materials depends on intelligent utilization of abundant plant resources. While biotechnology for biofuels has received considerable attention, the potential of enzymes to tailor plant polymers for novel biopolymer synthesis is comparatively unexplored.

In particular, enzymes that catalyze selective oxidation of specific hydroxyls to carbonyl and carboxyl groups can facilitate targeted chemical derivatizations of polysaccharides to create renewable polymers with preferred physical and chemical properties [1]. In this regard, galactose oxidase (GaOx) continues to be a promising catalyst for specific delivery of new functionality to plant polysaccharides. Current chemo-enzymatic protocols with GaOx begin by oxidizing galactose substituents in polysaccharides (e.g. galactoglucomannan, xyloglucan) that are suspended in solution. Oxidized polysaccharides can then be adsorbed to cellulose surfaces to modify the surface reactivity and/or barrier properties of cellulose-based materials. Although this is an elegant approach to expanding the range of cellulosic bioproducts, oxidation and derivatization of poly and oligo-saccharides can reduce their affinity to cellulose surfaces.

Accordingly, the aim of this study was to investigate the potential to oxidize xyloglucan and galactoglucomannan following adsorption of these polysaccharides to cellulose (Whatmann filter paper no. 1). Wild-type GaOx along with GaOx fused to a family 29 CBM from Piromyce equi were used in the analysis. Recent characterization of the GaOx RQW mutant fused to a cellulose-bind CBM3 will also be presented.