title: β-D-(1→4), β-D-(1→3) 'mixed linkage' xylans from red seaweeds of the order Nemaliales and Palmariales.
abstract: Xylans from five seaweeds belonging to the order Nemaliales (Galaxaura marginata, Galaxaura obtusata, Tricleocarpacylindrica, Tricleocarpa fragilis, and Scinaia halliae) and one of the order Palmariales (Palmaria palmata) collected on the Brazilian coasts were extracted with hot water and purified from acid xylomannans and/or xylogalactans through Cetavlon precipitation of the acid polysaccharides. The β-D-(1→4), β-D-(1→3) 'mixed linkage' structures were determined using methylation analysis and 1D and 2D NMR spectroscopy. The presence of large sequences of β-(1→4)-linked units suggests transient aggregates of ribbon- or helical-ordered structures that would explain the low optical rotations.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, CEP 81531-980 Curitiba-Paraná, Brazil.
authors.forename: Adriano G
authors.initials: AG
authors.lastname: Viana
authors.forename: Miguel D
authors.initials: MD
authors.lastname: Noseda
authors.forename: Alan G
authors.initials: AG
authors.lastname: Gonçalves
authors.forename: Maria Eugênia R
authors.initials: ME
authors.lastname: Duarte
authors.forename: Nair
authors.initials: N
authors.lastname: Yokoya
authors.forename: Maria C
authors.initials: MC
authors.lastname: Matulewicz
authors.forename: Alberto S
authors.initials: AS
authors.lastname: Cerezo
mesh_terms: D002236:Carbohydrate Conformation; D009682:Magnetic Resonance Spectroscopy; D008745:Methylation; D055620:Optical Phenomena; D000461:Rhodophyta / Q000737:chemistry*; D013237:Stereoisomerism; D014990:Xylans / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D014990:Xylans