title: Isolation and characterization of poly- and oligosaccharides from the red microalga Porphyridium sp.
abstract: The current study forms part of an ongoing research effort focusing on the elucidation of the chemical structure of the sulfated extracellular polysaccharide of the red microalga Porphyridium sp. (UTEX 637). We report here on the chemical structure of a fraction separated from an acidic crude extract of the polysaccharide, as investigated by methylation analysis, carboxyl reduction-methylation analysis, desulfation-methylation analysis, partial acid hydrolysis, Smith degradation, together with 1D and 2D (1)H and (13)C NMR spectroscopy. This fraction with a molar mass of 2.39x10(5)g mol(-1) comprised D- and L-Gal, D-Glc, D-Xyl, D-GlcA, and sulfate groups in a molar ratio of 1.0:1.1:2.1:0.2:0.7. The almost linear backbone of the fraction is composed of (1-->2)- or (1-->4)-linked d-xylopyranosyl, (1-->3)-linked L-galactopyranosyl, (1-->3)-linked D-glucopyranosyl, and (1-->3)-linked D-glucopyranosyluronic acid and comprises a possible acidic building unit: [(2 or 4)-beta-D-Xylp-(L-->3)]m-alpha-D-Glcp-(1-->3)-alpha-D-GLCPA-(1-->3)-L-Galp(l-->. Attached to the backbone are sulfate groups and nonreducing terminal D-xylopyranosyl and galactopyranosyl residues, which occur at the O-6 positions of Glc-derived moieties in the main chain.
authors.affiliation: Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
authors.forename: Shimona
authors.initials: S
authors.lastname: Geresh
authors.forename: Shoshana Malis
authors.initials: SM
authors.lastname: Arad
authors.forename: Oshrat
authors.initials: O
authors.lastname: Levy-Ontman
authors.forename: Wang
authors.initials: W
authors.lastname: Zhang
authors.forename: Yoram
authors.initials: Y
authors.lastname: Tekoah
authors.forename: Robert
authors.initials: R
authors.lastname: Glaser
mesh_terms: D002240:Carbohydrate Sequence; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D044665:Porphyridium / Q000737:chemistry*; D014990:Xylans / Q000737:chemistry
chemical_list: D009844:Oligosaccharides; D014990:Xylans; C038910:glucuronoxylan