Arabinoxylan fractionation on DEAE-cellulose chromatography influenced by protease pre-treatment

An arabinoxylan mixture was extracted with saturated barium hydroxide from a water unextractable residue of rye bran. The mixture was fractionated on an anion exchange column which was eluted with water, 0.0025 M sodium borate, 0.025 M sodium borate and 0.4 M sodium hydroxide. It was possible to fractionate the arabinoxylan mixture into fractions with different structural features. The fractionation was repeated with prior protease treatment of the arabinoxylan mixture, but most of the arabinoxylan did not bind to the column by any mechanism that the protease treatment affected. As the largest fraction was still eluted with 0.4 M sodium hydroxide. Protease treatment affected the proportion of disubstituted xylose residues (dXyl) in the water, 0.0025 M sodium borate and 0.025 M sodium borate fractions, indicating that protein associated with arabinoxylans with a high dXyl content is more liable to the protease treatment or that protein is mainly associated with these structures. This study gives indications that protein is involved in the separation mechanism of rye arabinoxylan on a DEAE-cellulose column.