Fig. 1

Structure of spruce glucuronoarabinoxylan and sites of action of specific hydrolytic enzymes. Spruce GAX consists of a backbone of β-1,4-linked Xylp residues substituted in places by α-1,3-linked Araf units and α-1,2 linked 4-O-MeGlcA. Several enzyme activities are required for the degradation of this highly decorated polymer