Polysaccharides of soy-beans. Part IV. Partial hydrolysis of the acidic polysaccharide complex from cotyledon meal

Abstract

Partial acid hydrolysis of the acidic polysaccharide complex from soy-bean cotyledon meal affords 4-O-β-D-galactopyranosyl-D-galactose, the polymer-homologous tri-, tetra-, penta-, and hexa-saccharides, 4-O-(α-D-galactopyranosyluronic acid)-D-galacturonic acid and the polymerhomologous trisaccharide, 2-O-(α-D-galacto-pyranosyluronic acid)-L-rhamnose, a tetrasaccharide containing alternating residues of galacturonic acid and rhamnose, and small amounts of three glucuronic acid-containing aldobiouronic acids. Partial acetolysis of the acetylated polysaccharide complex, followed by deacetylation of the products, gives a similar mixture of neutral and acidic oligosaccharides together with 2-O-α-L-fucopyranosyl-D-xylose, 2-O-β-D-galactopyranosyl-D-xylose, and acidic oligosaccharides containing galacturonic acid and contiguous rhamnose residues. Enzymic hydrolysis of partially degraded polysaccharide furnishes 3-O-β-D-xylopyranosyl-D-galacturonic acid and higher acidic oligosaccharides containing chains of 1 → 4 linked β-D-galactopyranose residues. Partial structures for the polysaccharide complex are discussed in the light of these and previous results, and the known structural features are compared with those of pectic acids and tragacanthic acid.