Structural characteristics of oxalate-soluble polysaccharides from Norway spruce (Picea abies) foliage

Structurally different polymers were derived from Picea abies foliage by successive extraction with water (PA(W)), HCl solution (PA(A)) and (NH4)(2)C2O4 solution (PA(O)). The P. abies foliage was found to contain basically low-methoxyl pectin extractable with an (NH4)(2)C2O4 solution. PA(W) was shown to comprise primarily arabinogalactan-proteins (AGPs); PA(A) was composed of mixed AGPs and pectic polysaccharides, with the latter prevailing; and polysaccharide PA(O) isolated in the highest yield included chiefly pectic polysaccharides. The major constituents of PA(O) were low-methoxyl and low-acetylated 1,4-alpha-D-galacturonan and partially acetylated RG-I. The sugar side chains of RG-I contained chiefly highly branched 1,5-alpha-L-arabinan and arabinogalactan type I as a minor constituent. RG-I whose side chains had 1,5-alpha-L-arabinan represented short regions alternating with non-acetylated and unmethylesterified galacturonan regions. In addition to pectins, polysaccharide PA(O) contained AGPs, xylanes and glucomannans, indicating that these polysaccharides are in an intimate interaction.