Structure of an anti-complementary arabinogalactan from the root of Angelica acutiloba Kitagawa.
Mild acid hydrolysis of an anti-complementary arabinogalactan (AGIIb-1), isolated from the roots of Angelica acutiloba Kitagawa, gave one neutral (N-I) and two acidic arabinogalactan (A-I and A-II) units and one neutral arabinan unit (N-II). The methyl-esterified rhamnogalacturonan cores of A-I and A-II were subjected to base-catalysed beta-elimination in the presence of sodium borodeuteride to give the neutral side-chains. Gel filtration showed that A-I contained a high-molecular-weight arabinogalactan and two oligosaccharides consisting of Ara and Gal or Ara as the side chains, and that A-II was composed of two high-molecular-weight arabinogalactans. Similar treatment of the acidic fraction, obtained by partial acid hydrolysis of A-I, gave mono- to tetra-galactosylgalactitol-1-d. Partial acid hydrolysis showed that the rhamnogalacturonan core of A-I contained the sequences --4)-GalA-(1--2)-Rha-(1-- and --4)-GalA-(1--4)-Rha-(1--. Digestion with exo-beta-D-galactosidase and Smith degradation indicated that N-I contained a (1--3)-linked galactan backbone with 6-inked galactosyl side-chains. The galactan components of A-I and A-II contained chains that were rich in 3-linked Gal. Fluorescent-labelling with 2-aminopyridine indicated that Ara was the reducing terminal in N-II, whereas it was Rha in A-I and A-II. The mild acid treatment of a different AGIIb-1 preparation gave an oligosaccharide fraction which consisted mainly of terminal and 3-linked Arap, 4- or 5-linked Ara, terminal, 4-linked, and 4,6-linked Gal, and terminal GlcA, and contained Gal and Rha as the reducing terminals.
Kiyohara
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Oriental Medicine Research Center of the Kitasato Institute, Tokyo, Japan.
Yamada
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D002240:Carbohydrate Sequence; D003169:Complement Inactivator Proteins; D005685:Galactans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008745:Methylation; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010944:Plants / Q000032:analysis*
D003169:Complement Inactivator Proteins; D005685:Galactans; C062640:anti-complementary arabinogalactan