title: Enzymatic fragmentation of carbohydrate moieties of radish arabinogalactan-protein and elucidation of the structures.
abstract: We investigated the structures of L-arabino-galactooligosaccharides released from the sugar moieties of a radish arabinogalactan-protein (AGP) by the action of exo-β-(1→3)-galactanase. We detected a series of neutral β-(1 → 6)-linked galactooligosaccharides forming branches of one to up to at least 19 consecutive Gal groups, together with corresponding acidic derivatives terminating in 4-O-methyl-glucuronic acid (4-Me-GlcA) at the non-reducing end. Some oligosaccharide chains of degree of polymerization (dp) higher than 3 for neutral, and 4 for acidic oligomers were modified with L-Araf residues. The acidic tetrasaccharide 4-Me-β-GlcA-(1 → 6)[α-L-Araf-(1 → 3)]-β-Gal-(1 → 6)-Gal was detected as an abundant L-Araf-containing oligosaccharide among these neutral and acidic oligomers. A pentasaccharide containing an additional L-Araf group attached to the L-Ara in the tetrasaccharide through an α-(1 → 5)-linkage was also found. We observed L-arabino-galactooligosaccharides substituted with single or disaccharide L-Araf units at different Gal residues along these neutral and acidic β-(1 → 6)-galactooligosaccharide chains, indicating that these side chains are highly variable in length and substituted variously with L-Araf residues.
authors.affiliation: a Division of Life Science , Graduate School of Science and Engineering, Saitama University , Saitama , Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Shimoda
authors.forename: Kohei
authors.initials: K
authors.lastname: Okabe
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kotake
authors.forename: Koji
authors.initials: K
authors.lastname: Matsuoka
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Koyama
authors.forename: Theodora
authors.initials: T
authors.lastname: Tryfona
authors.forename: Hui-Chung
authors.initials: HC
authors.lastname: Liang
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Tsumuraya
mesh_terms: D002240:Carbohydrate Sequence; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000737:chemistry* / Q000378:metabolism*; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D031224:Raphanus / Q000737:chemistry*; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D009088:Mucoproteins; D009844:Oligosaccharides; D010940:Plant Proteins; C006619:arabinogalactan proteins; D001616:beta-Galactosidase
keywords: L-arabino-galactooligosaccharide; arabinogalactan-protein; exo-β-(1→3)-galactanase; radish; α-L-arabinofuranosidase