title: Structural studies by stepwise enzymatic degradation of the main backbone of soybean soluble polysaccharides consisting of galacturonan and rhamnogalacturonan.
abstract: Soybean soluble polysaccharides (SSPS) extracted from soybean cotyledons are acidic polysaccharides and have a pectin-like structure. The results of a structural analysis of SSPS by using polygalacturonase (PGase) and rhamnogalacturonase (RGase) clarified that the main backbone consisted of galacturonan (GN) and rhamnogalacturonan (RG), which were composed of the diglycosyl repeating unit, -4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-. The side chains of beta-1,4-galactans, branched with fucose and arabinose residues, were linked to the C-4 side of rhamnose residues in the RG regions. The degree of polymerization (dps) of GN, which linked the RG regions together, was estimated to be about 4-10 residues, and some were modified with xylose residues on the C-3 side of the galacturonates. The dps of GN at the reducing end of SSPS was estimated to be about 7-9 residues. Moreover, the fragment of the basic structure of the RG region, -[4)-alpha-D-GalpA-(1-->2)-alpha-L-Rhap-(1-]2-, some of which had long-chain beta-1,4-galactans branched on the C-4 side of rhamnose residues, were liberated from SSPS by the RGase treatment. The dps of the galactan side chain was estimated to be about 43-47 residues by an analysis of the digestion products from the beta-galactosidase treatment.
authors.affiliation: Tsukuba R & D Center, Fuji Oil Co, Ltd, Ibaraki, Japan. 940080@so.fujioil.co.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nakamura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Furuta
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Maeda
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Takao
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Nagamatsu
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006026:Glycoside Hydrolases / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000737:chemistry / Q000378:metabolism; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism; D012995:Solubility; D013025:Glycine max / Q000737:chemistry* / Q000378:metabolism; D016339:Spectrometry, Mass, Fast Atom Bombardment
chemical_list: D009005:Monosaccharides; D010368:Pectins; D006026:Glycoside Hydrolases; C003181:polygalacturonic acid