Figure 5
![Figure 5](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13068-015-0284-1/MediaObjects/13068_2015_284_Fig5_HTML.gif)
MALDI-TOF MS spectra of xylan-RAC mixtures incubated with MtLPMO9A. b Birchwood xylan (BiWX; 2 mg mL−1) and c oat spelt xylan (OSX; 2 mg mL−1) in the presence of regenerated amorphous cellulose (RAC; 2 mg mL−1) after incubation of MtLPMO9A (10 mg g−1 substrate). Samples were incubated in a 50 mM ammonium acetate buffer (pH 5.0) for 24 h at 52°C with ascorbic acid addition (1 mM). MtLPMO9A incubation of BiWX and OSX with RAC addition releases non-oxidized and oxidized xylo- and gluco-oligosaccharides (XOSn, XOS #n *; GlcOSn, GluOS #n *). The presence of C4-oxidized XOSn*, and XOS #n oxidized at C1 to an aldonic acid (# + 16 Da) is shown. Non-oxidized GlcOSn and oxidized GlcOS #n * are less detectable due to abundance of xylo-oligosaccharides present. From BiWX also 4-O-methylglucoronic acid containing non-oxidized XOSn (GlcAmeXOSn) and 4-O-methylglucoronic acid containing oxidized XOS #n * (GlcAmeXOS #n *) are formed. a Illustrated structure of 4-O-methylglucoronic acid containing C1- and C4-oxidized XOSn.(GlcAmeXOS #n , GlcAmeXOSn*, respectively). Masses represent lithium adducts only. Double Li adducts are determined for C1-oxidized products (§ + 6 Da). MALDI-TOF MS analysis of BiWX and OSX in the presence of RAC after incubation of MtLPMO9A without ascorbic acid did not reveal detectable amounts of oxidized products (data not shown).