Figure 4.

HPAEC elution pattern of xylan–RAC mixtures incubated with MtLPMO9A. a Birchwood xylan (BiWX) and b oat spelt xylan (OSX) (2 mg mL⁻¹) in the presence and absence of regenerated amorphous cellulose (RAC; 2 mg mL⁻¹) after incubation with MtLPMO9A (12.5 mg g⁻¹ substrate). c HPAEC elution pattern of RAC after incubation with MtLPMO9A (12.5 mg g⁻¹ substrate). Samples were incubated in a 50 mM ammonium acetate buffer (pH 5.0) with ascorbic acid addition (1 mM). Incubation with MtLPMO9A of the two xylans and xylan–RAC mixtures, in the presence of ascorbic acid, results in the formation of non-oxidized linear xylo-oligosaccharides (XOS_n) and substituted xylo-oligosaccharides. Incubation of xylan–RAC mixtures with MtLPMO9A in the presence of ascorbic acid results in the formation of non-oxidized gluco-oligosaccharides (GlcOS_n) and oxidized gluco-oligosaccharides (GlcOS^#_n). The incubation of MtLPMO9A with BiWX–RAC and OSX–RAC mixture in the presence of ascorbic acid results in the formation of numerous products (black arrow, indicated as oxidized xylo-oligosaccharides XOS^#_n *), which are not present if MtLPMO9A was incubated with BiWX, OSX or RAC alone. The results of MALDI-TOF MS analysis of BiWX–RAC and OSX–RAC mixture incubated with MtLPMO9A in the presence of ascorbic acid are shown in Figure 5.