title: alpha-D-Glucuronosyl-(1-->3)-L-galactose, an unusual disaccharide from polysaccharides of the hornwort Anthoceros caucasicus.
abstract: Acid hydrolysis of cell wall-rich material from thalli of the hornwort Anthoceros caucasicus yielded substantial amounts of an unusual disaccharide (1). Hydrolysis of 1 yielded only GlcA, Gal and unhydrolysed 1. Compound 1 was identified as alpha-D-GlcpA-(1-->3)-L-Gal by 1H and 13C NMR spectroscopic analysis and by the susceptibility of its monosaccharide units to phosphorylation by enantiomer-specific kinases. Compound 1 was not detected in acid hydrolysates of other land plants including mosses, leafy and thalloid liverworts, lycopodiophytes and euphyllophytes; it was also absent from charophytes. The Anthoceros polysaccharide that yields 1 was partially extractable in cold aqueous buffer (pH 4.7) and Na(2)CO(3), but not in EDTA or NaOH, suggesting that it was not a typical pectin or hemicellulose. The yield of 1 from various polysaccharide fractions correlated with the yields of Xyl, suggesting a previously unreported polymer containing D-GlcA, L-Gal and Xyl. The existence of a unique polysaccharide in an evolutionarily isolated plant (Anthoceros) supports the view that major steps in plant phylogeny were accompanied by significant changes in cell wall composition.
authors.affiliation: The Edinburgh Cell Wall Group, Institute of Cell and Molecular Biology, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK.
authors.forename: Zoë A
authors.initials: ZA
authors.lastname: Popper
authors.forename: Ian H
authors.initials: IH
authors.lastname: Sadler
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Fry
mesh_terms: D002236:Carbohydrate Conformation; D002473:Cell Wall / Q000737:chemistry; D005591:Chemical Fractionation / Q000379:methods; D005690:Galactose / Q000031:analogs & derivatives* / Q000302:isolation & purification*; D005965:Glucuronates / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000378:metabolism; D010944:Plants / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*
chemical_list: D005965:Glucuronates; D011134:Polysaccharides; D017853:Phosphotransferases (Alcohol Group Acceptor); C020591:glucuronokinase; D005690:Galactose