L-Fucose-containing arabinogalactan-protein in radish leaves.
The carbohydrate moieties of arabinogalactan-proteins (AGPs) have β-(1 → 3)-galactan backbones to which side chains of (1 → 6)-linked β-Gal residues are attached through O-6. Some of these side chains are further substituted with other sugars. We investigated the structure of L-Fuc-containing oligosaccharides released from the carbohydrate moieties of a radish leaf AGP by digestion with α-L-arabinofuranosidase, followed by exo-β-(1 → 3)-galactanase. We detected a series of neutral β-(1 → 6)-galactooligosaccharides branching variously at O-3 of the Gal residues, together with corresponding acidic derivatives terminating in 4-O-methyl-GlcA (4-Me-GlcA) or GlcA at the non-reducing terminals. In neutral oligosaccharides with degree of polymerization (dp) mainly higher than 10, L-Fuc groups were attached through L-Ara residues as the sequence, α-L-Fucp-(1 → 2)-α-L-Araf-(1 →. This sequence was verified by isolation of the pentasaccharide α-L-Fuc-(1 → 2)-α-L-Araf-(1 → 3)-β-Gal-(1 → 6)-β-Gal-(1 → 6)-Gal upon digestion of the higher oligosaccharides with endo-β-(1 → 6)-galactanase. By contrast, in lower polymerized (predominantly dp 4) acidic oligosaccharides, L-Fuc groups were attached directly at the non-reducing terminals through α-(1 → 2)-linkages, resulting in the release of the tetrasaccharides, α-L-Fucp-(1 → 2)-β-GlcA-(1 → 6)-β-Gal-(1 → 6)-Gal and α-L-Fucp-(1 → 2)-β-4-Me-GlcA-(1 → 6)-β-Gal-(1 → 6)-Gal. In long acidic oligosaccharides with dp mainly higher than 13, L-Fuc groups localized on branches were attached to the uronic acids directly and/or L-Ara residues as in the neutral oligosaccharides.
Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Miho
M
Inaba
Department of Biochemistry and Molecular Biology, Faculty of Science, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Takuma
T
Maruyama
Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Yoshihisa
Y
Yoshimi
Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Toshihisa
T
Kotake
Division of Material Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Koji
K
Matsuoka
Division of Material Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan.
Tetsuo
T
Koyama
School of Biological Sciences, Department of Biochemistry, Cambridge University, Hopkins Building, The Downing site, Tennis Court Road, Cambridge, Cambridge CB2 1QW, UK.
Theodora
T
Tryfona
School of Biological Sciences, Department of Biochemistry, Cambridge University, Hopkins Building, The Downing site, Tennis Court Road, Cambridge, Cambridge CB2 1QW, UK.
Paul
P
Dupree
Division of Life Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570, Japan. Electronic address: tsumura@mail.saitama-u.ac.jp.
Yoichi
Y
Tsumuraya
D005643:Fucose / Q000737:chemistry* / Q000378:metabolism; D005685:Galactans / Q000737:chemistry* / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000378:metabolism; D006868:Hydrolysis; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D031224:Raphanus / Q000737:chemistry* / Q000378:metabolism
D005685:Galactans; D009844:Oligosaccharides; D005643:Fucose; D006026:Glycoside Hydrolases; C063901:exo-beta-(1--3)-D-galactanase; C019713:alpha-N-arabinofuranosidase; C005653:arabinogalactan
Arabinogalactan-protein; Exo-β-(1→3)-galactanase; Radish; Raphanus sativus L.; l-Fucose