Molecular characterization and solution properties of enzymatically tailored arabinoxylans

Two α-l-arabinofuranosidases with different substrate specificities were used to modify the arabinose-to-xylose ratio of cereal arabinoxylans: one enzyme (AXH-m) removed the l-arabinofuranosyl substituents from the monosubstituted xylopyranosyl residues and the other (AXH-d3) the (1 → 3)-linked l-arabinofuranosyl units from the disubstituted xylopyranosyl residue. In this study, we noticed that not only the arabinose-to-xylose ratio but also the position of the arabinofuranosyl substituents affects the water-solubility of arabinoxylans. The AXH-d3 treatment had no significant effect on the solution conformation of arabinoxylans, but the density of the arabinoxylan molecules decreased in DMSO solution after AXH-m modification. The possible heterogeneity of arabinoxylans complicated the interpretation of data describing the macromolecular properties of the enzymatically modified samples.