Polysaccharides of soy-beans. Part III. Extraction and fractionation of polysaccharides from cotyledon meal

Abstract

Extraction of defatted soy-bean cotyledon meal, after prior removal of soluble sugars and protein, with ethylenediaminetetra-acetic acid disodium salt furnished a mixture of an arabinogalactan and an acidic polysaccharide complex. The arabinogalactan has been shown to contain chains of 1 -4 linked p-D-galactopyranose residues in which every fourth or fifth residue carries through C-3 a side-chain containing, on the average, two L-arabinofuranose residues joined by a 1 __+ 5 linkage. The acidic polysaccharide complex has been shown to possess a highly branched structure with residues of galacturonic acid, galactose, arabinose, xylose, fucose, and rhamnose in which side-chains are terminated by galactopyranose, fucopyranose, xylopyranose, and arabinofuranose residues.KAWAMURA and his collaborators24 have shown that soy-bean cotyledons contain complex mixtures of polysaccharides which give on hydrolysis galacturonic acid , galactose, arabinose, xylose, fucose, and rhamnose, but knowledge of the structures of the soy-bean polysaccharides has been restricted to some of the constituents of the h u l l s . l ~~-~ In continuation of our studies of the structures of the polysaccharide components of soy-beans 137 we describe here the extraction and fractionation of polysaccharides from the cotyledons, the characterisation of an arabinogalactan, and the preliminary examination of an acidic polysaccharide complex.Defatted soy-bean cotyledon meal was extracted with boiling ethanol-water (4 : 1) to remove soluble sugars and to inactivate enzymes, and then with cold 0.2% sodium hydroxide, according to the procedure

Polysaccharides of Soybeans. VI. Neutral Polysaccharides from Cotyledon Meal

“…Paper chromatography of the neutral and acidic oligosaccharides formed on partial acid hydrolysis and acetolysis of the acidic polysaccharide complex showed that this preparation was at least qualitatively similar to the previously studied sample (1, 2) which had been extracted under harsher conditions. Likewise gas chromatography of the methyl glycosides formed on methanolysis of the methylated arabinogalactan showed that the parent polysaccharide was qualitatively similar to that studied previously by Morita and co-workers (3)(4)(5) and by ourselves (1,2).…”

“…In previous studies (1,2) an arabinogalactan and an acidic polysaccharide complex have been isolated from soybean cotyledon meal and the main structural features of these polysaccharides have been established. In parallel investigations Morita and co-workers (3)(4)(5) have obtained similar evidence for the structure of the arabinogalactan.…”

The Structure of Plant Cell Walls

“…Rhamnogalacturonans appear to be a common feature of all pectic polysaccharides. Pectic galactans containing a /3-1,4-linked galactan backbone have been isolated from soybean seed (10). The highly branched arabinan region of sycamore pectic polysaccharides contains similar linkages to those present in the pectic arabinans isolated from soybean (11), lemon peel (11), and mustard seed (11).…”

“…This enzyme has been highly purified (32), and the purified enzyme is able to remove most of the galacturonic acid from the isolated cell walls of a number of plants. This volumes (v/w) of 1:1 chloroform-methanol, 3 times with 10 volumes (v/w) of acetone, and then allowed to air dry. This procedure results in a yield of cell wall material equal to approximately 1% of the weight of the original cells.…”

CP-MAS NMR analysis of carbohydrate fractions of soybean hulls and endosperm

“…Some decades ago, soybean polysaccharides were investigated by Morita et al [3][4][5], Aspinall et al [6][7][8][9][10][11] and Labavitch et al [12]. Arabinogalactans and pectin-like polymers were proposed to occur in sodium hydroxide extracts.…”