Structural features of an arabinoxylan and rhamnogalacturonan derived from linseed mucilage.

The mucilage, obtained (6%) by aqueous extraction of linseed, on fractionation with Cetavlon gave precipitable (CeP, 58%) and non-precipitable (CeNP, 28%) fractions. Further fractionation on DEAE-cellulose furnished a series of fractions of which the water-eluted neutral fraction of CeNP and the 0.2M ammonium carbonate-eluted acidic fraction of CeP were homogeneous. The neutral fraction contained L-arabinose, D-xylose, and D-galactose (3.5:6.2:1), and the acidic fraction contained L-rhamnose, L-fucose, L-galactose and D-galacturonic acid (2.6:1:1.4:1.7). The neutral fraction was anarabinoxylan having a (1->4)-beta-D-xylan backbone to which arabinose and galactose side-chains were attached at positions 2 and/or 3. The acidic fraction had a backbone of (1->2)-linked alpha-L-rhamnopyranosyl and (1->4)-linked D-galactopyranosyluronic acid residues, with side-chains of fucose and galactose residues, the former essentially at the non-reducing end.