Figure 7. ¹H-NMR spectra of xylan from the gxm1/2/3 mutant overexpressing PtrGXMs.

Xylooligosaccharides generated by xylanase digestion of xylan were subjected to ¹H-NMR analysis. Resonances are labeled with the position of the assigned proton and the identity of the residue containing that proton. The resonances of H1 of α-d-GalA, H1 of α-l-Rha, H1 of 3-linked β-d-Xyl, H4 of α-d-GalA, and H2 of α-l-Rha are from the xylan reducing end tetrasaccharide sequence. G and M refer to the GlcA- and Me-α-GlcA-substituted xylosyl residues, respectively. Note the partial restoration of the resonances of Me-α-GlcA (red arrows) in the gxm1/2/3 mutant overexpressing PtrGXMs.